An Etymological Dictionary of Astronomy and Astrophysics

1. Any decapod crustacean of the suborder Brachyura, having the eyes on short stalks and a short, broad, more or less flattened body, the abdomen being small and folded under the thorax. → Cancer; → Crab nebula; → Crab pulsar.
   

2. Any of various other crustaceans, as the hermit crab, or other animals, as the horseshoe crab, resembling the true crabs (Dictionary.com).

Etymology (EN): M.E. crabbe; O.E. crabba, from Germanic *krab(b)- (cf. Low Ger. krabben “to scratch, claw”); PIE base *gerbh- “to scratch;” cf. Gk. graphein “to write.”

Etymology (PE): Xarcang “crab,” from Mid.Pers. karcang, cf. Lori qerženg from kar-, qer- + cang, ženg “claw.” The meaning of the first component, xar/qer, is not clear. It may be related to Av. xruta-, xraoždva- “hard,” as in xruždisma- “hard ground” (from xruždi- + zam-), and to the PIE *qarq- “to be hard.” In that case, the Pers. term for crab would literally mean “hard claw.”

1. Any decapod crustacean of the suborder Brachyura, having the eyes on short stalks and a short, broad, more or less flattened body, the abdomen being small and folded under the thorax. → Cancer; → Crab nebula; → Crab pulsar.
   

2. Any of various other crustaceans, as the hermit crab, or other animals, as the horseshoe crab, resembling the true crabs (Dictionary.com).

Etymology (EN): M.E. crabbe; O.E. crabba, from Germanic *krab(b)- (cf. Low Ger. krabben “to scratch, claw”); PIE base *gerbh- “to scratch;” cf. Gk. graphein “to write.”

Etymology (PE): Xarcang “crab,” from Mid.Pers. karcang, cf. Lori qerženg from kar-, qer- + cang, ženg “claw.” The meaning of the first component, xar/qer, is not clear. It may be related to Av. xruta-, xraoždva- “hard,” as in xruždisma- “hard ground” (from xruždi- + zam-), and to the PIE *qarq- “to be hard.” In that case, the Pers. term for crab would literally mean “hard claw.”

An expanding cloud of debris from the explosion of a → Type I supernova in the → constellation  → Taurus. Its light reached Earth in 1054 and
was visible to the naked eye even in the daytime. Lying about 6,300 → light-years away, the Crab nebula is an intense → radio source (Tau A), and also a source of X-rays and gamma-rays. The diameter of the → supernova remnant is about 6 light-years; it is expanding at velocity of 1000 km/sec.

See also: → crab; → nebula.

An expanding cloud of debris from the explosion of a → Type I supernova in the → constellation  → Taurus. Its light reached Earth in 1054 and
was visible to the naked eye even in the daytime. Lying about 6,300 → light-years away, the Crab nebula is an intense → radio source (Tau A), and also a source of X-rays and gamma-rays. The diameter of the → supernova remnant is about 6 light-years; it is expanding at velocity of 1000 km/sec.

See also: → crab; → nebula.

A → pulsar discovered in the center of the → Crab nebula in 1969. It is a highly magnetized → neutron star with a radius of 10-15 km that spins 30 times a second.

See also: → crab; → pulsar.

A → pulsar discovered in the center of the → Crab nebula in 1969. It is a highly magnetized → neutron star with a radius of 10-15 km that spins 30 times a second.

See also: → crab; → pulsar.

1. A bed for a baby that is usually designed to rock back and forth when pushed gently. → Newton’s cradle.
   

2. The place where something begins (Merriam-Webster.com).

Etymology (EN): M.E. cradel, from O.E cradol akin to O.H.G. kratto “basket,” Ger. Krätze “basket carried on the back;” Pers. gereh “knot;” Skt. granth- “to tie a knot” (Cheung 2007).

Etymology (PE): Gahvâré “cradle,” variants gâhvâré, gowvâré, govâré, from Mid.Pers. gâhwârag “cot, cradle.”

1. A bed for a baby that is usually designed to rock back and forth when pushed gently. → Newton’s cradle.
   

2. The place where something begins (Merriam-Webster.com).

Etymology (EN): M.E. cradel, from O.E cradol akin to O.H.G. kratto “basket,” Ger. Krätze “basket carried on the back;” Pers. gereh “knot;” Skt. granth- “to tie a knot” (Cheung 2007).

Etymology (PE): Gahvâré “cradle,” variants gâhvâré, gowvâré, govâré, from Mid.Pers. gâhwârag “cot, cradle.”

A ship or other vessel.

Etymology (EN): M.E., from O.E. cræft “strength, skill;” cf. Ger. Kraft, D. kracht, O.N. kraptr. The “ship” meaning comes from the expression “vessel of small craft (trade).”

Etymology (PE): Nâv “ship;” O.Pers./Av. *nāv-, O.Pers. nāviyā- “fleet;” cf. Skt. nau-, nava- “ship, boat;” Gk. naus.

A ship or other vessel.

Etymology (EN): M.E., from O.E. cræft “strength, skill;” cf. Ger. Kraft, D. kracht, O.N. kraptr. The “ship” meaning comes from the expression “vessel of small craft (trade).”

Etymology (PE): Nâv “ship;” O.Pers./Av. *nāv-, O.Pers. nāviyā- “fleet;” cf. Skt. nau-, nava- “ship, boat;” Gk. naus.

1. A bowl-like depression on the rigid surface of a planet, satellite, or asteroid
   usually caused by the high-speed impact of a colliding object.
   

2. A bowl-shaped cavity at the mouth of a volcano.
   

3. The Cup. A small → constellation with faint stars, in the Southern Hemisphere, that lies next to → Hydra, at about 11h 20m right ascension, 15° south declination. Abbreviation: Crt; genitive: Crateris.

Etymology (EN): From Gk. krater “a wide, two-handled bowl for mixing wine with water,” from kerannynai “to mix;” PIE base *kere- “to mix, confuse.”

Etymology (PE): Lâvak “a large wooden bowl for kneading dough.”
Kandâl “cavity, pit” in Qâeni, from kand- past tense stem of kandan “to dig” (Mid.Pers. kandan, O.Pers./Av. kan- “to dig,” Skt. khan- “to dig”) + -al, → -al.
Jâm “cup, chalice, goblet, bowl,” Mid.Pers. jâm “vessel, goblet; glass,” Av. yama- “glass, glass vessel,” yâmô.pacika- “baked glass;” related to Skt. camasa- “a vessel used at sacrifices for drinking Soma, kind of flat dish or cup?”

1. A bowl-like depression on the rigid surface of a planet, satellite, or asteroid
   usually caused by the high-speed impact of a colliding object.
   

2. A bowl-shaped cavity at the mouth of a volcano.
   

3. The Cup. A small → constellation with faint stars, in the Southern Hemisphere, that lies next to → Hydra, at about 11h 20m right ascension, 15° south declination. Abbreviation: Crt; genitive: Crateris.

Etymology (EN): From Gk. krater “a wide, two-handled bowl for mixing wine with water,” from kerannynai “to mix;” PIE base *kere- “to mix, confuse.”

Etymology (PE): Lâvak “a large wooden bowl for kneading dough.”
Kandâl “cavity, pit” in Qâeni, from kand- past tense stem of kandan “to dig” (Mid.Pers. kandan, O.Pers./Av. kan- “to dig,” Skt. khan- “to dig”) + -al, → -al.
Jâm “cup, chalice, goblet, bowl,” Mid.Pers. jâm “vessel, goblet; glass,” Av. yama- “glass, glass vessel,” yâmô.pacika- “baked glass;” related to Skt. camasa- “a vessel used at sacrifices for drinking Soma, kind of flat dish or cup?”

The lower part of an → impact crater bounded by the rising
→ crater rim.

See also: → crater; → floor.

The lower part of an → impact crater bounded by the rising
→ crater rim.

See also: → crater; → floor.

That part an → impact crater that extends above the height of the local surface, usually in a circular or elliptical pattern.

See also: → crater; → rim.

That part an → impact crater that extends above the height of the local surface, usually in a circular or elliptical pattern.

See also: → crater; → rim.

The process by which craters form on the surface of Solar System objects.

Etymology (EN): From → crater + → -ing

Etymology (PE): From lâvak or kandâl, → crater, + zâyi from zâ- present tense stem of zâdan “to give birth,” Mid.Pers. zâtan, Av. zan- “to bear, give birth to a child, be born,” infinitive zazâite, zâta- “born,” cf. Skt. janati “begets, bears,” L. gignere “to beget,” PIE base *gen- “to give birth, beget.”

The process by which craters form on the surface of Solar System objects.

Etymology (EN): From → crater + → -ing

Etymology (PE): From lâvak or kandâl, → crater, + zâyi from zâ- present tense stem of zâdan “to give birth,” Mid.Pers. zâtan, Av. zan- “to bear, give birth to a child, be born,” infinitive zazâite, zâta- “born,” cf. Skt. janati “begets, bears,” L. gignere “to beget,” PIE base *gen- “to give birth, beget.”

A small crater often beside a larger one on the surface of the Moon or solid planets.

Etymology (EN): From → crater + -let diminutive suffix.

Etymology (PE): Lâvakcé, kandâlcé from lâvak, kandâl, → crater,

• -cé diminutive suffix.

A small crater often beside a larger one on the surface of the Moon or solid planets.

Etymology (EN): From → crater + -let diminutive suffix.

Etymology (PE): Lâvakcé, kandâlcé from lâvak, kandâl, → crater,

• -cé diminutive suffix.

1. To cause to come into existence.
   
2. To produce or bring about by a course of action or behavior.

Etymology (EN): M.E., from L. creatus, p.p. of creare “to make, bring forth, produce,” akin to crescere “arise, grow,” → crescent.

Etymology (PE): Âfaridan, âfarin- “to create” (related to nifrin, nefrin “curse”); Mid.Pers. âfrin- “to create, bless;” Av. frī- “to rejoice, please;”
cf. Skt. pray- “to please, enjoy, satisfy,” O.H.G. friten “to look after;” Ger. frei, → free.

1. To cause to come into existence.
   
2. To produce or bring about by a course of action or behavior.

Etymology (EN): M.E., from L. creatus, p.p. of creare “to make, bring forth, produce,” akin to crescere “arise, grow,” → crescent.

Etymology (PE): Âfaridan, âfarin- “to create” (related to nifrin, nefrin “curse”); Mid.Pers. âfrin- “to create, bless;” Av. frī- “to rejoice, please;”
cf. Skt. pray- “to please, enjoy, satisfy,” O.H.G. friten “to look after;” Ger. frei, → free.

1. The act of producing or causing to exist.
   
2. The act of being created. See also → creation operator.

See also: Verbal noun of → create.

1. The act of producing or causing to exist.
   
2. The act of being created. See also → creation operator.

See also: Verbal noun of → create.

An operator that acts on the → eigenstate describing the → harmonic oscillator to raise its → energy level by one step. The creation operator is the → Hermitian conjugate operator of the → annihilation operator.

See also: → creation; → operator.

An operator that acts on the → eigenstate describing the → harmonic oscillator to raise its → energy level by one step. The creation operator is the → Hermitian conjugate operator of the → annihilation operator.

See also: → creation; → operator.

The religious belief that considers the account of creation given in Genesis to be a scientific description and rejects the Big Bang theory and the theory of evolution. Creationism is a → pseudoscience. Same as “creation science” and “scientific creationism.”

See also: → creation; → -ism.

The religious belief that considers the account of creation given in Genesis to be a scientific description and rejects the Big Bang theory and the theory of evolution. Creationism is a → pseudoscience. Same as “creation science” and “scientific creationism.”

See also: → creation; → -ism.

1a) Commendation or honor given for some action, quality, etc.

1b) A source of pride or honor.

1c) The ascription or acknowledgment of something as due or properly attributable to a person, institution, etc.

1d) Influence or authority resulting from the confidence of others or from one’s reputation.

1e) A sum of money due to a person; anything valuable standing on the credit side of an account:

2. To believe; put confidence in; trust; have faith in (Dictionary.com).

Etymology (EN): M.E., from M.Fr. crédit “belief, trust,” from It. credito, from L. creditum “a loan, thing entrusted to another,” from p.p. of credere “to trust, entrust, believe.”

Etymology (PE): Arjé, from arj “esteem, honor, dignity; price, worth, value,” variant of arz “price, value,” arzidan “to be worth;” Mid.Pers. arz- “to be worth;” Av. arj- “to be worth,” arəjaiti “it is worth;” Proto-Ir. *Harj- “to be worth;” cf. Skt. arh- “to earn, be worth;” Gk. alphein “to earn, to obtain;” Lith. alga “salary, pay.” “to be woth.” Arjé dâdan with dâdan “to give, grant, yield,” → datum.

1a) Commendation or honor given for some action, quality, etc.

1b) A source of pride or honor.

1c) The ascription or acknowledgment of something as due or properly attributable to a person, institution, etc.

1d) Influence or authority resulting from the confidence of others or from one’s reputation.

1e) A sum of money due to a person; anything valuable standing on the credit side of an account:

2. To believe; put confidence in; trust; have faith in (Dictionary.com).

Etymology (EN): M.E., from M.Fr. crédit “belief, trust,” from It. credito, from L. creditum “a loan, thing entrusted to another,” from p.p. of credere “to trust, entrust, believe.”

Etymology (PE): Arjé, from arj “esteem, honor, dignity; price, worth, value,” variant of arz “price, value,” arzidan “to be worth;” Mid.Pers. arz- “to be worth;” Av. arj- “to be worth,” arəjaiti “it is worth;” Proto-Ir. *Harj- “to be worth;” cf. Skt. arh- “to earn, be worth;” Gk. alphein “to earn, to obtain;” Lith. alga “salary, pay.” “to be woth.” Arjé dâdan with dâdan “to give, grant, yield,” → datum.

An alternative name for Saturn’s C ring, which is a wide but faint ring located inside the B Ring. Discovered in 1850 by William and George Bond, it was termed “crepe” because it seemed to be composed of darker material than the brighter A and B Rings.

Etymology (EN): Crepe, from Fr. crêpe, from O.Fr. crespe, from L. crispa, fem. of crispus “curled;” → ring.

Etymology (PE): Halqé, → ring; parniyân “a kind of fine painted silk, a mantle of such silk.”

An alternative name for Saturn’s C ring, which is a wide but faint ring located inside the B Ring. Discovered in 1850 by William and George Bond, it was termed “crepe” because it seemed to be composed of darker material than the brighter A and B Rings.

Etymology (EN): Crepe, from Fr. crêpe, from O.Fr. crespe, from L. crispa, fem. of crispus “curled;” → ring.

Etymology (PE): Halqé, → ring; parniyân “a kind of fine painted silk, a mantle of such silk.”

Rays of sunlight that appear to diverge from a single point in the sky when parallel columns of light, partially blocked by clouds, pour through gaps in clouds. They result from
light scattering and an optical effect called perspective.

Etymology (EN): Crepuscular “of, pertaining to, or resembling twilight,” from L. crepuscul(um), “twilight, dusk,” from crepus-, from creper “dusky, dark.”

Etymology (PE): Partowhâ “rays,” from partow, → ray; nimtâbi “of, pertaining to, or resembling nimtâb” → twilight.

Rays of sunlight that appear to diverge from a single point in the sky when parallel columns of light, partially blocked by clouds, pour through gaps in clouds. They result from
light scattering and an optical effect called perspective.

Etymology (EN): Crepuscular “of, pertaining to, or resembling twilight,” from L. crepuscul(um), “twilight, dusk,” from crepus-, from creper “dusky, dark.”

Etymology (PE): Partowhâ “rays,” from partow, → ray; nimtâbi “of, pertaining to, or resembling nimtâb” → twilight.

The figure of the → Moon or an → inferior planet when it is less than half illuminated, as seen by the → observer.

Etymology (EN): From O.Fr. croissant, from L. crescentum, p.p. of crescere “to grow, increase; spring forth,” from PIE base *ker- “to grow” (cf. Gk. kouros “boy,” kore “girl,” Pers. dialects Laki korr “son, boy,” Lori kor “son, boy,” Malayeri kora “boy,” Kordi kur “son,” Arm. serem “bring forth,” serim “be born”).

Etymology (PE): Helâl from Ar. Barn “the new moon,” from Proto-Iranian *aparnâ- “unfilled,” from negation prefix → a- + parnâ- “full;” cf. Mid.Pers. purr mâh “full moon,” Av. pərənô-mâh- “full moon,” Skt. purna-mâs- “full moon;” → full;
→ moon.

The figure of the → Moon or an → inferior planet when it is less than half illuminated, as seen by the → observer.

Etymology (EN): From O.Fr. croissant, from L. crescentum, p.p. of crescere “to grow, increase; spring forth,” from PIE base *ker- “to grow” (cf. Gk. kouros “boy,” kore “girl,” Pers. dialects Laki korr “son, boy,” Lori kor “son, boy,” Malayeri kora “boy,” Kordi kur “son,” Arm. serem “bring forth,” serim “be born”).

Etymology (PE): Helâl from Ar. Barn “the new moon,” from Proto-Iranian *aparnâ- “unfilled,” from negation prefix → a- + parnâ- “full;” cf. Mid.Pers. purr mâh “full moon,” Av. pərənô-mâh- “full moon,” Skt. purna-mâs- “full moon;” → full;
→ moon.

The first sighting of the → New Moon after its → conjunction with the Sun. Although the date and time of each New Moon can be computed exactly, the visibility of the lunar → crescent as a function of the → Moon’s age depends upon many factors and cannot be predicted with certainty. The sighting within one day of New Moon is usually difficult. The crescent at this time is quite thin, has a low surface brightness, and can easily be lost in the → twilight. Generally, the lunar crescent will become visible to suitably-located, experienced observers with good sky conditions about one day after New Moon. However, the time that the crescent actually becomes visible varies from one month to another. The visibility depends on sky conditions and the location, experience, and preparation of the observer. Ignoring atmospheric conditions, the size and brightness of the lunar crescent depend on the → elongation which in turn depends on several factors:

1. The Moon’s elongation at New Moon (the elongation of the Moon at New Moon is not necessarily 0).

2. The speed of the Moon in its elliptical orbit.

3. The distance of the Moon, and

4. The observer’s location (parallax).

The combined effect of the first three factors gives geocentric elongation of the Moon from the Sun at an age of one day which can vary between about 10 and 15 degrees. This large range of possible elongations in the one-day-old Moon is critical (US Naval Observatory).

See also: → crescent; → moon; → visibility.

The first sighting of the → New Moon after its → conjunction with the Sun. Although the date and time of each New Moon can be computed exactly, the visibility of the lunar → crescent as a function of the → Moon’s age depends upon many factors and cannot be predicted with certainty. The sighting within one day of New Moon is usually difficult. The crescent at this time is quite thin, has a low surface brightness, and can easily be lost in the → twilight. Generally, the lunar crescent will become visible to suitably-located, experienced observers with good sky conditions about one day after New Moon. However, the time that the crescent actually becomes visible varies from one month to another. The visibility depends on sky conditions and the location, experience, and preparation of the observer. Ignoring atmospheric conditions, the size and brightness of the lunar crescent depend on the → elongation which in turn depends on several factors:

1. The Moon’s elongation at New Moon (the elongation of the Moon at New Moon is not necessarily 0).

2. The speed of the Moon in its elliptical orbit.

3. The distance of the Moon, and

4. The observer’s location (parallax).

The combined effect of the first three factors gives geocentric elongation of the Moon from the Sun at an age of one day which can vary between about 10 and 15 degrees. This large range of possible elongations in the one-day-old Moon is critical (US Naval Observatory).

See also: → crescent; → moon; → visibility.

The width of the lit area of the → Moon measured along the Moon’s diameter.

See also: → crescent; → width.

The width of the lit area of the → Moon measured along the Moon’s diameter.

See also: → crescent; → width.

The highest point or upper part of a wave.

Etymology (EN): From O.Fr. creste “tuft, comb,” from L. crista “tuft, plume; rooster’s comb.”

Etymology (PE): Setiq “summit; anything standing upright,” from O.Pers./Av. sta- “to stand, stand still; set,” Mod.Pers. istâdan “to stand”
(cf. Skt. sthâ- “to stand,” Gk. histemi “put, place, weigh,” stasis “a standing still,” L. stare “to stand”)

• adj. suffix -iq, variants -ig, -ik, → -ics.

The highest point or upper part of a wave.

Etymology (EN): From O.Fr. creste “tuft, comb,” from L. crista “tuft, plume; rooster’s comb.”

Etymology (PE): Setiq “summit; anything standing upright,” from O.Pers./Av. sta- “to stand, stand still; set,” Mod.Pers. istâdan “to stand”
(cf. Skt. sthâ- “to stand,” Gk. histemi “put, place, weigh,” stasis “a standing still,” L. stare “to stand”)

• adj. suffix -iq, variants -ig, -ik, → -ics.

A period of → geologic time which began at the end of the → Jurassic period approximately 145 million years ago and extended to approximately 65 million years ago.

Etymology (EN): From L. cretaceus, from cret(a) “chalk, clay,” + → -aceous, because the geological remains of this period contain heightened chalk deposits.

Etymology (PE): Gacâsâ, from gac “chalk,” Mid.Pers. gac

• -âsâ, → -aceous.

A period of → geologic time which began at the end of the → Jurassic period approximately 145 million years ago and extended to approximately 65 million years ago.

Etymology (EN): From L. cretaceus, from cret(a) “chalk, clay,” + → -aceous, because the geological remains of this period contain heightened chalk deposits.

Etymology (PE): Gacâsâ, from gac “chalk,” Mid.Pers. gac

• -âsâ, → -aceous.

The → mass extinction event that destroyed the dinosaurs and a majority of other species on Earth approximately 65 million years ago. This event is believed to have been the impact of a 10 km-size → asteroid or → comet nucleus and its aftereffects, including a severe → impact winter. The collision would have released the energy equivalent to 100 million megatonnes (teratonnes) of → TNT, i.e. more than 10⁹ times the energy of the atomic bomb dropped on Hiroshima on August 6, 1945.

Same as the → Cretaceous-Tertiary event.

See also: → Cretaceous; → Paleogene;
→ extinction; → event.

The → mass extinction event that destroyed the dinosaurs and a majority of other species on Earth approximately 65 million years ago. This event is believed to have been the impact of a 10 km-size → asteroid or → comet nucleus and its aftereffects, including a severe → impact winter. The collision would have released the energy equivalent to 100 million megatonnes (teratonnes) of → TNT, i.e. more than 10⁹ times the energy of the atomic bomb dropped on Hiroshima on August 6, 1945.

Same as the → Cretaceous-Tertiary event.

See also: → Cretaceous; → Paleogene;
→ extinction; → event.

See → Cretaceous-Paleogene extinction event.

See also: K, representing the “→ Cretaceous period,” and T the “→ Tertiary;” → event.

See → Cretaceous-Paleogene extinction event.

See also: K, representing the “→ Cretaceous period,” and T the “→ Tertiary;” → event.

A group of persons acting or working together.

Etymology (EN): M.E. crewe “augmentation, reinforcement, body of soldiers,” from M.Fr. crue, from O.Fr. creue “an increase, recruit, military reinforcement,” from p.p. of creistre “grow,” from L. crescere “grow, arise,” → crescent.

Etymology (PE): Koran, variants korand, korang “a troop, a circle of people” (Dehxodâ).

A group of persons acting or working together.

Etymology (EN): M.E. crewe “augmentation, reinforcement, body of soldiers,” from M.Fr. crue, from O.Fr. creue “an increase, recruit, military reinforcement,” from p.p. of creistre “grow,” from L. crescere “grow, arise,” → crescent.

Etymology (PE): Koran, variants korand, korang “a troop, a circle of people” (Dehxodâ).

An action or an instance of negligence that is deemed injurious to the public welfare
or morals or to the interests of the state and that is legally prohibited (Dictionary.com).

Etymology (EN): M.E., from O.Fr. crimne, from L. crimen “charge, indictment, accusation; offense.”

Etymology (PE): Bazah, from Mid.Pers. bazag “crime, misdeed,” bazagkâr “evil-doer,” Parthian bzg “evil, wicked.”

An action or an instance of negligence that is deemed injurious to the public welfare
or morals or to the interests of the state and that is legally prohibited (Dictionary.com).

Etymology (EN): M.E., from O.Fr. crimne, from L. crimen “charge, indictment, accusation; offense.”

Etymology (PE): Bazah, from Mid.Pers. bazag “crime, misdeed,” bazagkâr “evil-doer,” Parthian bzg “evil, wicked.”

1. Of the nature of or involving crime.
   

2. A person guilty or convicted of a crime.

See also: L. criminalis, → crime; → -al.

1. Of the nature of or involving crime.
   

2. A person guilty or convicted of a crime.

See also: L. criminalis, → crime; → -al.

A decisive stage or turning point in the course of something, especially in a sequence of events or an acute disease.

Etymology (EN): M.E., from Latinized from of Gk. krisis “turning point in a disease,” literally “judgment, selection,” from krinein “to separate, decide, judge;cf. " L. cribrum “sieve,” crimen “judgment, crime;” → critique.

Etymology (PE): Paržané, from paržan, present stem of paržanidan “to separate, sift, → critique,”

• -é a suffix of relation.

A decisive stage or turning point in the course of something, especially in a sequence of events or an acute disease.

Etymology (EN): M.E., from Latinized from of Gk. krisis “turning point in a disease,” literally “judgment, selection,” from krinein “to separate, decide, judge;cf. " L. cribrum “sieve,” crimen “judgment, crime;” → critique.

Etymology (PE): Paržané, from paržan, present stem of paržanidan “to separate, sift, → critique,”

• -é a suffix of relation.

1. Notably sharp, clear-cut, and clear.
   

2. Noticeably neat (Merriam-Webster.com).

Etymology (EN): M.E, from O.E., from L. crispus “curled,” cognate with Walsh crych “curly.”

Etymology (PE): Tuj (Kurmanji Kurd.) variant of tiz, → sharp.

1. Notably sharp, clear-cut, and clear.
   

2. Noticeably neat (Merriam-Webster.com).

Etymology (EN): M.E, from O.E., from L. crispus “curled,” cognate with Walsh crych “curly.”

Etymology (PE): Tuj (Kurmanji Kurd.) variant of tiz, → sharp.

A classical set that allows only full membership or no membership at all for its elements, as contrasted with a → fuzzy set. Crisp set can be viewed as a restricted case of the more general fuzzy set concept.

A classical set that allows only full membership or no membership at all for its elements, as contrasted with a → fuzzy set. Crisp set can be viewed as a restricted case of the more general fuzzy set concept.

A standard or rule that can serve as basis for a judgment or decision.

Etymology (EN): From Gk. kriterion “means for judging, standard,” from krites “judge,” from krinein “to separate, distinguish, judge.” L. cribrum “sieve” *krei- “to sieve, discriminate, distinguish.”

Etymology (PE): Sanjidâr verbal noun from sanjid- past tense stem of sanjidan “to compare; to measure” (Mid.Pers. sanjidan “to weigh,” from present tense stem sanj-, Av. θanj- “to draw, pull;” Proto-Iranian *θanj-) + suffix -âr.

A standard or rule that can serve as basis for a judgment or decision.

Etymology (EN): From Gk. kriterion “means for judging, standard,” from krites “judge,” from krinein “to separate, distinguish, judge.” L. cribrum “sieve” *krei- “to sieve, discriminate, distinguish.”

Etymology (PE): Sanjidâr verbal noun from sanjid- past tense stem of sanjidan “to compare; to measure” (Mid.Pers. sanjidan “to weigh,” from present tense stem sanj-, Av. θanj- “to draw, pull;” Proto-Iranian *θanj-) + suffix -âr.

A person who judges, evaluates, or criticizes.

Etymology (EN): M.E., from M.Fr. critique, from L. criticus “a judge, literary critic,” → critique.

Etymology (PE): Paržangar, from paržan present stem of paržanidan, “criticize”, → critique, + -kâr, -gar suffixes of agent nouns, → -or.

A person who judges, evaluates, or criticizes.

Etymology (EN): M.E., from M.Fr. critique, from L. criticus “a judge, literary critic,” → critique.

Etymology (PE): Paržangar, from paržan present stem of paržanidan, “criticize”, → critique, + -kâr, -gar suffixes of agent nouns, → -or.

1. Of or pertaining to → critics or → criticism.
   

2. Of, relating to, or being a state or level at which a significant change takes place (Dictionary.com).

See also: → critic; → -al.

1. Of or pertaining to → critics or → criticism.
   

2. Of, relating to, or being a state or level at which a significant change takes place (Dictionary.com).

See also: → critic; → -al.

Angle of incidence of light proceeding from a denser medium toward a thinner, at which grazing refraction occurs (angle of refraction 90°).

See also: → critical; → angle.

Angle of incidence of light proceeding from a denser medium toward a thinner, at which grazing refraction occurs (angle of refraction 90°).

See also: → critical; → angle.

The upper value of mass that a → Bonnor-Ebert sphere must have in order that → hydrodynamic equilibrium be maintained. This → critical mass is given by: M_crit = 1.18 (a⁴/G^3/2)P_ext^-1/2, where a = (kT/m)^1/2 is the isothermal → sound speed inside the sphere, G is the → gravitational constant, and P_ext the pressure of the external medium (see, e.g., F. H. Shu, 1977, ApJ 214, 488).

See also: → critical; → Bonnor-Ebert mass.

The upper value of mass that a → Bonnor-Ebert sphere must have in order that → hydrodynamic equilibrium be maintained. This → critical mass is given by: M_crit = 1.18 (a⁴/G^3/2)P_ext^-1/2, where a = (kT/m)^1/2 is the isothermal → sound speed inside the sphere, G is the → gravitational constant, and P_ext the pressure of the external medium (see, e.g., F. H. Shu, 1977, ApJ 214, 488).

See also: → critical; → Bonnor-Ebert mass.

1. Cosmology: The average density of matter in the Universe that would be needed to eventually halt the → cosmic expansion. In a spatially → flat Universe, the critical density is expressed by ρ_c = (3c²/8πG)H_t², where c is the → speed of light, G is the → gravitational constant, and H_t the → Hubble parameter. The critical density is currently 9.3 × 10^-30g cm^-3, about 6 hydrogen atoms per cubic meter (for H₀ = 70 km s^-1 Mpc^-1).
   

2. In → gravitational lensing, the minimum density that would be needed by an intervening object to bend light rays. It is expressed by: Σ = (c²/4πG)(d_os/d_old_ls), where c is the speed of light, G is the gravitational constant, d_os, d_ol, and d_ls represent angular diameter distances between the observer and the source, the observer and the lens, and the lens and the source respectively. It has units of mass per unit solid angle.
   

3. Radiative processes: The density at which the collisional → de-excitation rate equals the → radiative transition rate. The critical density for level j is given by:

n_c = Σ_{i < j} A_ji = Σ_{i ≠ j} q_ji, where A_ji is the → Einstein coefficient of → spontaneous emission
and q_ji is the rate for collisional de-excitation of → energy level&nbspj, summed over all possible processes. This expression often simplifies to the ratio of two numbers, since in many cases there is a single important path for emission and a dominant collisional de-excitation process. In the low density limit the → emissivity is proportional to the product N_e (electron density) x N_i (ion density),
whereas for densities exceeding the critical density, the emissivity is proportional to N_i. Thus, line emission in a nebula occurs most efficiently near the critical density.

See also: → critical; → density.

1. Cosmology: The average density of matter in the Universe that would be needed to eventually halt the → cosmic expansion. In a spatially → flat Universe, the critical density is expressed by ρ_c = (3c²/8πG)H_t², where c is the → speed of light, G is the → gravitational constant, and H_t the → Hubble parameter. The critical density is currently 9.3 × 10^-30g cm^-3, about 6 hydrogen atoms per cubic meter (for H₀ = 70 km s^-1 Mpc^-1).
   

2. In → gravitational lensing, the minimum density that would be needed by an intervening object to bend light rays. It is expressed by: Σ = (c²/4πG)(d_os/d_old_ls), where c is the speed of light, G is the gravitational constant, d_os, d_ol, and d_ls represent angular diameter distances between the observer and the source, the observer and the lens, and the lens and the source respectively. It has units of mass per unit solid angle.
   

3. Radiative processes: The density at which the collisional → de-excitation rate equals the → radiative transition rate. The critical density for level j is given by:

n_c = Σ_{i < j} A_ji = Σ_{i ≠ j} q_ji, where A_ji is the → Einstein coefficient of → spontaneous emission
and q_ji is the rate for collisional de-excitation of → energy level&nbspj, summed over all possible processes. This expression often simplifies to the ratio of two numbers, since in many cases there is a single important path for emission and a dominant collisional de-excitation process. In the low density limit the → emissivity is proportional to the product N_e (electron density) x N_i (ion density),
whereas for densities exceeding the critical density, the emissivity is proportional to N_i. Thus, line emission in a nebula occurs most efficiently near the critical density.

See also: → critical; → density.

Of a fissile material (²³⁵U or ²³⁹Pu),
the minimum mass needed for a sustained nuclear chain reaction, as in an atomic bomb.

See also: → critical; → mass.

Of a fissile material (²³⁵U or ²³⁹Pu),
the minimum mass needed for a sustained nuclear chain reaction, as in an atomic bomb.

See also: → critical; → mass.

The → metallicity of a → star-forming  → molecular cloud when → cooling → rates by → metals dominate the → gravitational  → heating during → protostellar collapse. The minimum → Jeans mass achieved by gravitational → fragmentation depends on the presence/absence of → coolants in the cloud. Since cooling rate in metal lines is more efficient than in primordial molecular lines (H₂ and HD), metals favor fragmentation in gas and formation of → low-mass stars.

See also: → critical; → metallicity.

The → metallicity of a → star-forming  → molecular cloud when → cooling → rates by → metals dominate the → gravitational  → heating during → protostellar collapse. The minimum → Jeans mass achieved by gravitational → fragmentation depends on the presence/absence of → coolants in the cloud. Since cooling rate in metal lines is more efficient than in primordial molecular lines (H₂ and HD), metals favor fragmentation in gas and formation of → low-mass stars.

See also: → critical; → metallicity.

The strong → scattering that occurs in a fluid near the → critical point. Large density fluctuations bring about inhomogeneities of all sizes. This results in the scattering of light at all wavelengths giving a milky appearance to the fluid.

See also: → critical; → opalescence.

The strong → scattering that occurs in a fluid near the → critical point. Large density fluctuations bring about inhomogeneities of all sizes. This results in the scattering of light at all wavelengths giving a milky appearance to the fluid.

See also: → critical; → opalescence.

1. Velocity of → fluid through a pipe at which the motion changes from → laminar to → turbulent flow.
   

2. Same as → break-up velocity.

See also: → critical; → velocity.

1. Velocity of → fluid through a pipe at which the motion changes from → laminar to → turbulent flow.
   

2. Same as → break-up velocity.

See also: → critical; → velocity.

1. The act of passing judgment as to the merits of anything.
   

2. The act or art of analyzing and evaluating or judging the quality of a literary or artistic work, musical performance, art exhibit, dramatic production, etc.
   

3. A critical comment, article, or essay; → critique (Dictionary.com).

See also: → critic; → -ism.

1. The act of passing judgment as to the merits of anything.
   

2. The act or art of analyzing and evaluating or judging the quality of a literary or artistic work, musical performance, art exhibit, dramatic production, etc.
   

3. A critical comment, article, or essay; → critique (Dictionary.com).

See also: → critic; → -ism.

To judge or discuss the merits and faults of.

Etymology (EN): → critic; → -ize.

To judge or discuss the merits and faults of.

Etymology (EN): → critic; → -ize.

1. An article or essay criticizing a literary or other work; detailed evaluation; review.
   

2. A criticism or critical comment on some problem, subject, etc.
   

3. The art or practice of criticism (Dictionary.com).

Etymology (EN): M.E. critick, changed to Fr. spelling, from M.Fr. critique, from L. criticus “a judge, literary critic,” from Gk. kritikos “able to make judgments,” from krinein “to sift, separate, decide;” cognate with Pers. qarbâl “sieve,” → sieve of Eratosthenes, from PIE base *krei- “to sift, distinguish.”

Etymology (PE): Paržan, from Tâti Karingâni puržen, Zazaki pirožin, Tabari parjan “sieve,” related to parvizan “sieve” (Laki vežonen “to sift”); ultimately from Proto-Ir. *pari-uaicana-, from the base *uaic- “to separate, sift, select, sort out;” Av. vaēc- “to select, sort out, sift;” Mod.Pers. bixtan, biz- “to sift.”

1. An article or essay criticizing a literary or other work; detailed evaluation; review.
   

2. A criticism or critical comment on some problem, subject, etc.
   

3. The art or practice of criticism (Dictionary.com).

Etymology (EN): M.E. critick, changed to Fr. spelling, from M.Fr. critique, from L. criticus “a judge, literary critic,” from Gk. kritikos “able to make judgments,” from krinein “to sift, separate, decide;” cognate with Pers. qarbâl “sieve,” → sieve of Eratosthenes, from PIE base *krei- “to sift, distinguish.”

Etymology (PE): Paržan, from Tâti Karingâni puržen, Zazaki pirožin, Tabari parjan “sieve,” related to parvizan “sieve” (Laki vežonen “to sift”); ultimately from Proto-Ir. *pari-uaicana-, from the base *uaic- “to separate, sift, select, sort out;” Av. vaēc- “to select, sort out, sift;” Mod.Pers. bixtan, biz- “to sift.”

1a) Cultivated plants or agricultural produce, such as grain, vegetables, or fruit, considered as a group (e.g. a wheat crop, farmers harvest crop).

1b) The total yield of such produce in a particular season or place.

2. To harvest (TheFreeDictionary.com).

Etymology (EN): M.E. crop, croppe, from O.E. cropp “head or top of a sprout or herb, any part of a medicinal plant except the root,” also “bird’s craw,” cognate with O.H.G. kropf, Du. krop “crop.”

Etymology (PE): Kâšâr, literally “yield of cultivating,” from kâš, contratction of kâšt-, kâštan “to cultivate, plant, sow,”

• âr contraction of âvar present stem of âvardan “to bring; to cause, produce,” → format.

1a) Cultivated plants or agricultural produce, such as grain, vegetables, or fruit, considered as a group (e.g. a wheat crop, farmers harvest crop).

1b) The total yield of such produce in a particular season or place.

2. To harvest (TheFreeDictionary.com).

Etymology (EN): M.E. crop, croppe, from O.E. cropp “head or top of a sprout or herb, any part of a medicinal plant except the root,” also “bird’s craw,” cognate with O.H.G. kropf, Du. krop “crop.”

Etymology (PE): Kâšâr, literally “yield of cultivating,” from kâš, contratction of kâšt-, kâštan “to cultivate, plant, sow,”

• âr contraction of âvar present stem of âvardan “to bring; to cause, produce,” → format.

1a) The Southern Cross, → Crux.

1b) A figure or pattern formed by the intersection of two lines.

2a) (adj.) Involving interchange; reciprocal.

2b) Lying or passing crosswise; intersecting.

3. To move or go across (something); traverse or intersect.

Etymology (EN): M.E. cros, from O.E., probably from Old Norse kross, from O.Ir. cros, from L. crux “stake, cross.”

Etymology (PE): Calipâ, loanword from Aramaic.
Xâj loanword from Arm.
Gozaštan, Mid.Pers. vitartan “to pass,” Sogdian wytr “to go,” O.Pers./Av. vitar- “to put across,” from prefix vi- “away, apart,” + tar- “to cross over” (Skt. tr- “to cross over,” tarati “crosses,” cf. Av. taro, Skt. tirah “through, beyond,” L. trans “beyond,” Ger. durch, E. through; PIE base *tr- “through”).

1a) The Southern Cross, → Crux.

1b) A figure or pattern formed by the intersection of two lines.

2a) (adj.) Involving interchange; reciprocal.

2b) Lying or passing crosswise; intersecting.

3. To move or go across (something); traverse or intersect.

Etymology (EN): M.E. cros, from O.E., probably from Old Norse kross, from O.Ir. cros, from L. crux “stake, cross.”

Etymology (PE): Calipâ, loanword from Aramaic.
Xâj loanword from Arm.
Gozaštan, Mid.Pers. vitartan “to pass,” Sogdian wytr “to go,” O.Pers./Av. vitar- “to put across,” from prefix vi- “away, apart,” + tar- “to cross over” (Skt. tr- “to cross over,” tarati “crosses,” cf. Av. taro, Skt. tirah “through, beyond,” L. trans “beyond,” Ger. durch, E. through; PIE base *tr- “through”).

In radio astronomy, the process performed by a → cross correlator or the result of the process.

See also: → cross; → correlation.

In radio astronomy, the process performed by a → cross correlator or the result of the process.

See also: → cross; → correlation.

In radio interferometry, a device that multiplies together the signals received by each pair of antennas in an array and performs several operations on the signal (filtering out the noise added to the signal by the receiver electronics, correcting for the Doppler shift and geometric delay due to the position and motion of the antennas). The correlated signal, corresponding to the spatial frequency given by the distance between the two antennas, is then combined with the other spatial frequency to reconstruct the map of the source.

See also: → cross; → correlator.

In radio interferometry, a device that multiplies together the signals received by each pair of antennas in an array and performs several operations on the signal (filtering out the noise added to the signal by the receiver electronics, correcting for the Doppler shift and geometric delay due to the position and motion of the antennas). The correlated signal, corresponding to the spatial frequency given by the distance between the two antennas, is then combined with the other spatial frequency to reconstruct the map of the source.

See also: → cross; → correlator.

A device producing cross dispersion.

See also: → cross; → disperser.

A device producing cross dispersion.

See also: → cross; → disperser.

Dispersion of a light beam by using two dispersing elements (grating, grism), one for separating spectral orders, the other for resolving spectral features within an order.

See also: → cross; → dispersion.

Dispersion of a light beam by using two dispersing elements (grating, grism), one for separating spectral orders, the other for resolving spectral features within an order.

See also: → cross; → dispersion.

The identification of an object in a data base or catalog and matching it with the same object identified in another catalog.

See also: → cross; → identification.

The identification of an object in a data base or catalog and matching it with the same object identified in another catalog.

See also: → cross; → identification.

Same as → vector product.

See also: → cross; → product.

Same as → vector product.

See also: → cross; → product.

Reference from one part or element of a book or data catalog to something in another for further information.

See also: → cross; → reference.

Reference from one part or element of a book or data catalog to something in another for further information.

See also: → cross; → reference.

1. Math: The intersection of a plane with a geometric figure, usually at right angles to an axis of symmetry.
   

2. Physics: A quantity that expresses the effective area that a given particle presents as a target to another incident particle, giving a measure of the probability that the incident particle will induce a particular atomic or nuclear reaction. Also called collision cross section. The cross section has the dimensions of a surface. In nuclear and particle physics, the commonly used units for the cross section are the barn and cm².

See also: In classical mechanics, the cross section for the collision of a point particle with a hard sphere is just be the surface of a section through the middle of the sphere. This explains the name “cross section.” → cross; → section.

1. Math: The intersection of a plane with a geometric figure, usually at right angles to an axis of symmetry.
   

2. Physics: A quantity that expresses the effective area that a given particle presents as a target to another incident particle, giving a measure of the probability that the incident particle will induce a particular atomic or nuclear reaction. Also called collision cross section. The cross section has the dimensions of a surface. In nuclear and particle physics, the commonly used units for the cross section are the barn and cm².

See also: In classical mechanics, the cross section for the collision of a point particle with a hard sphere is just be the surface of a section through the middle of the sphere. This explains the name “cross section.” → cross; → section.

A spectrograph that utilizes cross dispersion.

See also: → cross; → dispersion; → spectrograph.

A spectrograph that utilizes cross dispersion.

See also: → cross; → dispersion; → spectrograph.

A system of two perpendicular fine threads of wire placed in the focus of the eyepiece of an optical instrument and used as a sighting reference.

Etymology (EN): → cross; → hair.

Etymology (PE): Târbast, from târ + bast. The first component târ “thread, string, wire,” cognate with tanidan, tan- “to spin, twist, weave,” → tension; the second component bast “to bind; to arrange” (past stem of bastan, from Mid.Pers. bastan/vastan “to bind, shut,” → band.

A system of two perpendicular fine threads of wire placed in the focus of the eyepiece of an optical instrument and used as a sighting reference.

Etymology (EN): → cross; → hair.

Etymology (PE): Târbast, from târ + bast. The first component târ “thread, string, wire,” cognate with tanidan, tan- “to spin, twist, weave,” → tension; the second component bast “to bind; to arrange” (past stem of bastan, from Mid.Pers. bastan/vastan “to bind, shut,” → band.

A concept used for checking the stability of a group of mass such as a → cluster of galaxies or a → star cluster. The crossing time is given by t_c = R/V, where R is the average projected radial distance of group members from the center of mass and V the Gaussian dispersion in internal velocity.

See also: → cross; → time.

A concept used for checking the stability of a group of mass such as a → cluster of galaxies or a → star cluster. The crossing time is given by t_c = R/V, where R is the average projected radial distance of group members from the center of mass and V the Gaussian dispersion in internal velocity.

See also: → cross; → time.

Any of several large oscine birds of the genus Corvus, of the family Corvidae, having a long, stout bill, lustrous black plumage, and a wedge-shaped tail (Dictionary.com).

Etymology (EN): O.E. crawe, imitative of the bird’s cry; cf. O.Saxon kraia; Du. kraai; O.H.G. chraja; Ger. Kräke; L. corvus “a raven,” Gk. korax; cognate with Pers. kalâq, → raven.

Etymology (PE): Zâq “crow, raven,” of unknown origin.

Any of several large oscine birds of the genus Corvus, of the family Corvidae, having a long, stout bill, lustrous black plumage, and a wedge-shaped tail (Dictionary.com).

Etymology (EN): O.E. crawe, imitative of the bird’s cry; cf. O.Saxon kraia; Du. kraai; O.H.G. chraja; Ger. Kräke; L. corvus “a raven,” Gk. korax; cognate with Pers. kalâq, → raven.

Etymology (PE): Zâq “crow, raven,” of unknown origin.

1a) A large number of persons gathered closely together; throng.

1b) Any large number of persons.

1c) Any group or set of persons with something in common.

2. To gather in large numbers; throng; swarm (Dictionary.com).
   → crowded, → crowded field, → crowding.

Etymology (EN): M.E. crowden, from O.E. crudan “to press, crush;” akin to
M.Du. cruden “to press, push,” M.H.G. kroten “to press, oppress,” Norwegian kryda “to crowd.”

Etymology (PE): Capiré (Dehxodâ), variants cabiré, capar “crowd,
troop, people gathered for something.” Capiré, from capir, from capar, ultimately from Proto-Ir. *ui-par-, from *par- “to fill;” cf. Av. pər- “to fill, stuff with,” pouru- “full, much, many;” O.Pers. paru- “much, many;” Pers. anbâr “ricks, storehouse,” por, bol “full, much, many;” PIE *pel- “to fill;” → population.

1a) A large number of persons gathered closely together; throng.

1b) Any large number of persons.

1c) Any group or set of persons with something in common.

2. To gather in large numbers; throng; swarm (Dictionary.com).
   → crowded, → crowded field, → crowding.

Etymology (EN): M.E. crowden, from O.E. crudan “to press, crush;” akin to
M.Du. cruden “to press, push,” M.H.G. kroten “to press, oppress,” Norwegian kryda “to crowd.”

Etymology (PE): Capiré (Dehxodâ), variants cabiré, capar “crowd,
troop, people gathered for something.” Capiré, from capir, from capar, ultimately from Proto-Ir. *ui-par-, from *par- “to fill;” cf. Av. pər- “to fill, stuff with,” pouru- “full, much, many;” O.Pers. paru- “much, many;” Pers. anbâr “ricks, storehouse,” por, bol “full, much, many;” PIE *pel- “to fill;” → population.

Filled so that there is little or no room for anyone or anything else.
→ crowded field.

See also: Past participle of → crowd.

Filled so that there is little or no room for anyone or anything else.
→ crowded field.

See also: Past participle of → crowd.

An area on the sky where a large number of objects, commonly stars, are seen gathered together, usually as revealed by imaging.

See also: → crowded; → field.

An area on the sky where a large number of objects, commonly stars, are seen gathered together, usually as revealed by imaging.

See also: → crowded; → field.

1. The state or action of filling a particular place in large numbers.
   

2. For a → field of view, state of containing a large number of objects.

See also: Verbal noun of → crowd.

1. The state or action of filling a particular place in large numbers.
   

2. For a → field of view, state of containing a large number of objects.

See also: Verbal noun of → crowd.

The process of procuring needed services by soliciting a large group of people outside the demanding company, society, or institute. Two examples of crowdsourcing in astronomy involve → variable star studies and search for → meteorites.

See also: Combination of → crowd and → outsourcing.

The process of procuring needed services by soliciting a large group of people outside the demanding company, society, or institute. Two examples of crowdsourcing in astronomy involve → variable star studies and search for → meteorites.

See also: Combination of → crowd and → outsourcing.

An optical, alkali-lime glass which is harder than → flint glass, and has a lower → index of refraction and lower → dispersion. It is used in the production of → compound lenses.

See also: Such named because of the crown-like shape given to the blank after the process of blowing the glass; M.E. coroune, from O.Fr. corone, from L. corona “crown,” originally “wreath, garland;” cf. Gk. korone “anything curved, kind of crown;” → glass.

An optical, alkali-lime glass which is harder than → flint glass, and has a lower → index of refraction and lower → dispersion. It is used in the production of → compound lenses.

See also: Such named because of the crown-like shape given to the blank after the process of blowing the glass; M.E. coroune, from O.Fr. corone, from L. corona “crown,” originally “wreath, garland;” cf. Gk. korone “anything curved, kind of crown;” → glass.

A curve, on the pressure versus specific volume plane,
representing the locus of all the theoretically possible states that can be attained by the → detonation products of an → explosive. The Crussard curve relates to the → Hugoniot curve through a translation caused by the chemical energy liberated during the detonation. The Crussard curve consists of several portions characterizing various burning regimes: detonations (strong and weak), a forbidden region, and → deflagrations (weak and strong).

See also: Named after the French engineer Jules Louis Crussard (1876-1959), who conducted several pioneering studies in mining techniques, in particular on shock waves (Ondes de choc et onde explosive, Bulletin de la Société de l’industrie minérale de Saint-Etienne, 4e série, tome VI, 1907); → curve.

A curve, on the pressure versus specific volume plane,
representing the locus of all the theoretically possible states that can be attained by the → detonation products of an → explosive. The Crussard curve relates to the → Hugoniot curve through a translation caused by the chemical energy liberated during the detonation. The Crussard curve consists of several portions characterizing various burning regimes: detonations (strong and weak), a forbidden region, and → deflagrations (weak and strong).

See also: Named after the French engineer Jules Louis Crussard (1876-1959), who conducted several pioneering studies in mining techniques, in particular on shock waves (Ondes de choc et onde explosive, Bulletin de la Société de l’industrie minérale de Saint-Etienne, 4e série, tome VI, 1907); → curve.

Any more or less hard or stiff outer covering or surface. → Earth’s crust.

Etymology (EN): M.E., from O.Fr. crouste from L. crusta “rind, crust, shell, bark;” cf. Skt. krud- “make hard, thicken;” Av. xruzdra- “hard;”
Gk. kryos “icy cold,” krystallos “ice, crystal;” Lett. kruwesis “frozen mud;” O.H.G. hrosa “ice, crust;” O.E. hruse “earth;” PIE base *kreus- “to begin to freeze, form a crust.”

Etymology (PE): Pusté, → shell.

Any more or less hard or stiff outer covering or surface. → Earth’s crust.

Etymology (EN): M.E., from O.Fr. crouste from L. crusta “rind, crust, shell, bark;” cf. Skt. krud- “make hard, thicken;” Av. xruzdra- “hard;”
Gk. kryos “icy cold,” krystallos “ice, crystal;” Lett. kruwesis “frozen mud;” O.H.G. hrosa “ice, crust;” O.E. hruse “earth;” PIE base *kreus- “to begin to freeze, form a crust.”

Etymology (PE): Pusté, → shell.

The Southern Cross. A small but brilliant → constellation in the southern hemisphere, at 12h 30m right ascension, 60° south declination. Also known as → Southern Cross. The constellation contains four bright stars so situated that they depict the extremities of a Latin cross. Abbreviation Cru; genitive Crucis.

Etymology (EN): L. crux “cross, gibbet” is a rendering of the Gk. stauros “an upright stake or pole,” in the Vulgate, the Latin translation of the Bible attributed to Saint Jerome at the end of the fourth century A.D.

Etymology (PE): Calipâ, loanword from Aramean.

The Southern Cross. A small but brilliant → constellation in the southern hemisphere, at 12h 30m right ascension, 60° south declination. Also known as → Southern Cross. The constellation contains four bright stars so situated that they depict the extremities of a Latin cross. Abbreviation Cru; genitive Crucis.

Etymology (EN): L. crux “cross, gibbet” is a rendering of the Gk. stauros “an upright stake or pole,” in the Vulgate, the Latin translation of the Bible attributed to Saint Jerome at the end of the fourth century A.D.

Etymology (PE): Calipâ, loanword from Aramean.

A branch of physics that studies the methods of producing very low temperatures (below 150 °C) and the behavior of materials and processes at those temperatures.

Etymology (EN): From cryo- “freezing” + -gen(y) “having to do with production” + -ics.
Cryo-, from Gk. kryos “icy cold,” krystallos “ice, crystal,” PIE base *kreus- “to begin to freeze, form a crust;” cf. L. crusta “crust, shell, bark,” Skt. krud- “make hard, thicken;” Av. xruzdra- “hard,” Lett. kruwesis “frozen mud;” O.H.G. hrosa “ice, crust;” O.E. hruse “earth.”
-geny, from Gk. geneia, from genes “born,” cf. Av. zan- “to bear, give birth to a child, be born,” infinitive zazâite, zâta- “born,” cf. Skt. janati “begets, bears,” L. gignere “to beget,” PIE base *gen- “to give birth, beget.”
→ -ics.

Etymology (PE): Zamâzâyik, from zam “cold (weather)” + zâyi “generating”

• -ik.
  

Mod.Pers. zam “cold,” Mid.Pers. zam “winter,” Av. zimô “winter,” Skt. hima- “cold, frost,” Ossetic zymæg/zumæg “winter,” Gk. xeimon “winter,” L. hiems “winter,” Lith. ziema “winter,” PIE *gheim- “snow, winter.”
Zâyi, from zâ- present tense stem of zâdan “to give birth,” Mid.Pers. zâtan, Av. zan- “to bear, give birth to a child, be born,” infinitive zazâite, zâta- “born,” cf. Skt. janati “begets, bears,” L. gignere “to beget,”
PIE base *gen- “to give birth, beget,” as above.
→ -ics.

A branch of physics that studies the methods of producing very low temperatures (below 150 °C) and the behavior of materials and processes at those temperatures.

Etymology (EN): From cryo- “freezing” + -gen(y) “having to do with production” + -ics.
Cryo-, from Gk. kryos “icy cold,” krystallos “ice, crystal,” PIE base *kreus- “to begin to freeze, form a crust;” cf. L. crusta “crust, shell, bark,” Skt. krud- “make hard, thicken;” Av. xruzdra- “hard,” Lett. kruwesis “frozen mud;” O.H.G. hrosa “ice, crust;” O.E. hruse “earth.”
-geny, from Gk. geneia, from genes “born,” cf. Av. zan- “to bear, give birth to a child, be born,” infinitive zazâite, zâta- “born,” cf. Skt. janati “begets, bears,” L. gignere “to beget,” PIE base *gen- “to give birth, beget.”
→ -ics.

Etymology (PE): Zamâzâyik, from zam “cold (weather)” + zâyi “generating”

• -ik.
  

Mod.Pers. zam “cold,” Mid.Pers. zam “winter,” Av. zimô “winter,” Skt. hima- “cold, frost,” Ossetic zymæg/zumæg “winter,” Gk. xeimon “winter,” L. hiems “winter,” Lith. ziema “winter,” PIE *gheim- “snow, winter.”
Zâyi, from zâ- present tense stem of zâdan “to give birth,” Mid.Pers. zâtan, Av. zan- “to bear, give birth to a child, be born,” infinitive zazâite, zâta- “born,” cf. Skt. janati “begets, bears,” L. gignere “to beget,”
PIE base *gen- “to give birth, beget,” as above.
→ -ics.

An apparatus for maintaining an enclosed area at a stable low temperature especially below 0°C.

See also: Cryostat, from cryo- “freezing,” → cryogenics + suffix → -stat.

An apparatus for maintaining an enclosed area at a stable low temperature especially below 0°C.

See also: Cryostat, from cryo- “freezing,” → cryogenics + suffix → -stat.

A solidified substance in which the constituent atoms, ions, or molecules form a three-dimensionally periodic arrangement.

Etymology (EN): O.E. cristal “clear ice, clear mineral,” from O.Fr. cristal, from L. crystallum “crystal, ice,” from Gk. krystallos, from kryos “frost,” from PIE base *kreus- “to begin to freeze, form a crust,” → cryogenics.

Etymology (PE): Bolur, from Mid.Pers. bêlûr “crystal,” Manichean Parthian bylwr, maybe of Indian origin, Pali veluriya- “a precious stone;” cf. Skt. vaidurya-, perhaps related to Tamil veliru, vilar “to become pale,” or to the southern Indian city Velur, modern Belur. The Mid.Pers. word is perhaps the carrier between the Indian word and the Gk. beryllos, which has given rise to L. beryllus, O.Fr. beryl, E. beryl “the beryllium aluminum silicate, Be₃Al₂Si₆O₁₈.”

A solidified substance in which the constituent atoms, ions, or molecules form a three-dimensionally periodic arrangement.

Etymology (EN): O.E. cristal “clear ice, clear mineral,” from O.Fr. cristal, from L. crystallum “crystal, ice,” from Gk. krystallos, from kryos “frost,” from PIE base *kreus- “to begin to freeze, form a crust,” → cryogenics.

Etymology (PE): Bolur, from Mid.Pers. bêlûr “crystal,” Manichean Parthian bylwr, maybe of Indian origin, Pali veluriya- “a precious stone;” cf. Skt. vaidurya-, perhaps related to Tamil veliru, vilar “to become pale,” or to the southern Indian city Velur, modern Belur. The Mid.Pers. word is perhaps the carrier between the Indian word and the Gk. beryllos, which has given rise to L. beryllus, O.Fr. beryl, E. beryl “the beryllium aluminum silicate, Be₃Al₂Si₆O₁₈.”

The network of the points in space at which the atoms, molecules, or ions of a → crystal are regularly repeated.

See also: → crystal; → lattice.

The network of the points in space at which the atoms, molecules, or ions of a → crystal are regularly repeated.

See also: → crystal; → lattice.

The geometric framework to which a crystal may be referred and the arrangement of atoms or electron density distribution relative to that framework, usually determined by X-ray diffraction measurements.

See also: → crystal; → structure.

The geometric framework to which a crystal may be referred and the arrangement of atoms or electron density distribution relative to that framework, usually determined by X-ray diffraction measurements.

See also: → crystal; → structure.

One of seven possible basic crystal types that is defined by the relations between the axis lengths and angles of its unit cell. Crystal systems can produce an infinite → lattice by successive translations in three-dimensional space so that each lattice point has an identical environment. The seven crystal systems are: → cubic, → orthorhombic, tetragonal, trigonal, hexagonal, monoclinic, and triclinic.

See also: → crystal; → system.

One of seven possible basic crystal types that is defined by the relations between the axis lengths and angles of its unit cell. Crystal systems can produce an infinite → lattice by successive translations in three-dimensional space so that each lattice point has an identical environment. The seven crystal systems are: → cubic, → orthorhombic, tetragonal, trigonal, hexagonal, monoclinic, and triclinic.

See also: → crystal; → system.

1. Of or like crystal; clear; transparent.
   

2. Formed by → crystallization.
   

3. Composed of crystals.
   

4. Pertaining to crystals or their formation (Dictionary.com).

See also: Adjective from → crystal.

1. Of or like crystal; clear; transparent.
   

2. Formed by → crystallization.
   

3. Composed of crystals.
   

4. Pertaining to crystals or their formation (Dictionary.com).

See also: Adjective from → crystal.

A → doubly convex, → transparent body in the → eye, situated behind the → iris, that focuses incident light on the → retina (Dictionary.com).

See also: → crystalline; → lens; → eye.

A → doubly convex, → transparent body in the → eye, situated behind the → iris, that focuses incident light on the → retina (Dictionary.com).

See also: → crystalline; → lens; → eye.

An arrangement and interrelationship of parts that is of → crystalline nature.

See also: → crystalline; → structure.

An arrangement and interrelationship of parts that is of → crystalline nature.

See also: → crystalline; → structure.

1. A state of molecular structure in some resins attributed to the existence of solid crystals with a definite geometric form.
   

2. The percentage of a polymer sample that has formed crystals (J. W. Gooch, Encyclopedic Dictionary of Polymers).

See also: → crystalline; → -ity.

1. A state of molecular structure in some resins attributed to the existence of solid crystals with a definite geometric form.
   

2. The percentage of a polymer sample that has formed crystals (J. W. Gooch, Encyclopedic Dictionary of Polymers).

See also: → crystalline; → -ity.

A process by which a homogeneous solution becomes crystal.

Etymology (EN): Noun from crystallize, → crystal.

Etymology (PE): Noun from bolur, from verb boluridan “to crystallize” + verbal noun suffix -eš.

A process by which a homogeneous solution becomes crystal.

Etymology (EN): Noun from crystallize, → crystal.

Etymology (PE): Noun from bolur, from verb boluridan “to crystallize” + verbal noun suffix -eš.

The science of forms, properties, and structure of crystals.

See also: → crystal; → -graphy; → -logy.

The science of forms, properties, and structure of crystals.

See also: → crystal; → -graphy; → -logy.