An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

Chemistry: The number of covalent bonds which an atom can from. The sharing of electrons to form chemical bonds. → equivalence.

From → co- + valence, from L. valentia "strength, worth," valere "to be worth; be strong."

Ham-arzâyi, from ham-→ co- + arzâyi, from arzidan "to be worth," arzân "worthy; of small value, cheap," arj "esteem, honour, price, worth," Mid.Pers. arz "value, worth," arzidan "be worth," arzân "valuable;" Av. arəjaiti "is worth," arəja- "valuable," arəg- "to be worth;" cf. Skt. arh- "to be worth, to earn," árhant- "worthy person;" Gk. alphanein "to bring in as profit," alphein "to ear, obtain;" Lith. algà "salary, pay;" PIE base *alg^wh- "to earn; price, value."

A chemical bond between two atoms of the same or different elements, in which each atom contributes one electron to be shared in a pair.

Covalent, adj. of → covalence; → bond.

In statistics, a measure of linear dependence. For two random variables X and Y with expectations m_x and m_y, the covariance is E{(X - m_x)(Y - m_y)}.

From co-, → com-, + → variance.

From ham-, → com-, + vartâyi, → variance.

In physics, having the property of remaining invariant in form under a Lorentz transformation.

→ com-; → variance.

A tensor whose components are distinguished by → subscript indices.

→ covariant; → tensor.

1) To spread over an area or surface.
2) Something that covers.

From M.E., from O.Fr. covrir, from L. cooperire "to cover over, overwhelm, bury," from the intensive prefix → com- + operire "to close, cover."

Pušidan "to cover; to put on," → envelope; pušeš, verbal noun of pušidan.

1) General: The extent to which something is covered.
2) Astro.: The total area of the sky observed in a particular → sky survey. See also → fractional sky coverage.
3) The area within which a radio signal sent by a transmitter is received reliably .
4) In film making, the shooting of a scene from various views and using various exposures.

From → cover + -age a suffix forming abstract nouns.

→ cover.

The female of bovine animals.

M.E. cou, cognate with Pers. Gâv, as below.

Mid.Pers. "bull, cow;" Av. gao-, gāvuš; cf. Skt. go-, gáus; Gk. bous ";" L. bos "ox, bull, cow;" O.E. cu "cow;" Ger. Kuh "cow;" PIE *g^wows "cow."

A model of the internal structure of → massive stars in which a → convective core is surrounded by a large → radiative envelope. However, recent studies point to the presence of a thin → convection zone in the outer envelope of hot massive stars, beneath the → photosphere, which is caused by opacity peaks associated with iron and helium ionization. See also → iron convection zone.

After Thomas Cowling (1906-1990), a British astronomer, who put forward the model; → model.

→ chemically peculiar star.

→ chemically peculiar star.

Same as → charge-parity symmetry.

→ charge; → parity; → symmetry.

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).

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."

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.

→ 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.

→ 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).

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).

Gahvâré "cradle," variants gâhvâré, gowvâré, govâré, from Mid.Pers. gâhwârag "cot, cradle."

A ship or other vessel.

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)."

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.

From Gk. krater "a wide, two-handled bowl for mixing wine with water," from kerannynai "to mix;" PIE base *kere- "to mix, confuse."

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.

→ crater; → floor.

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

→ crater; → rim.

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

From → crater + → -ing

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."