An Etymological Dictionary of Astronomy and Astrophysics

An empirical power-law correlation between the luminosity (L) and the velocity dispersion of stars (σ) in the center of a elliptical galaxies.
The original relation can be expressed mathematically as: L ∝ σ^γ, where the index γ is observed to be approximately equal to 4, but depends on the range of galaxy luminosities that is fitted. → Tully-Fisher relation.

See also: After the astronomers Sandra M. Faber and Robert Earl Jackson, who
first noted this relation in 1976 (ApJ 204, 668); → relation.

An empirical power-law correlation between the luminosity (L) and the velocity dispersion of stars (σ) in the center of a elliptical galaxies.
The original relation can be expressed mathematically as: L ∝ σ^γ, where the index γ is observed to be approximately equal to 4, but depends on the range of galaxy luminosities that is fitted. → Tully-Fisher relation.

See also: After the astronomers Sandra M. Faber and Robert Earl Jackson, who
first noted this relation in 1976 (ApJ 204, 668); → relation.

1. A short tale to teach a moral lesson, often with animals or inanimate objects as characters.
   

2. A story not founded on fact.
   

3. A story about supernatural or extraordinary persons or incidents; legend (Dictionary.com).

Etymology (EN): M.E. able, fabel, fabul, from O.Fr. fable “story, fable, tale; drama, play, fiction; lie, falsehood,” from L. fabula “story, story with a lesson, tale, narrative, account; the common talk, news,” literally “that which is told,” from fari “speak, tell,” from PIE root *bha- “speak.”

Etymology (PE): Afsâné, from Proto-Ir. *abi-sanhana-, from *sanh- “to declare, explain;” cf. O.Pers. θaⁿh- “to declare, say;”
Av. səngh- “to declare;” → speech.

1. A short tale to teach a moral lesson, often with animals or inanimate objects as characters.
   

2. A story not founded on fact.
   

3. A story about supernatural or extraordinary persons or incidents; legend (Dictionary.com).

Etymology (EN): M.E. able, fabel, fabul, from O.Fr. fable “story, fable, tale; drama, play, fiction; lie, falsehood,” from L. fabula “story, story with a lesson, tale, narrative, account; the common talk, news,” literally “that which is told,” from fari “speak, tell,” from PIE root *bha- “speak.”

Etymology (PE): Afsâné, from Proto-Ir. *abi-sanhana-, from *sanh- “to declare, explain;” cf. O.Pers. θaⁿh- “to declare, say;”
Av. səngh- “to declare;” → speech.

A type of interferometer wherein the beam of light undergoes multiple reflections between two closely spaced partially silvered surfaces. Part of the light is transmitted each time the light reaches the second surface, resulting in multiple offset beams which can interfere with each other. The large number of interfering rays produces an interferometer with extremely high resolution, somewhat like the multiple slits of a diffraction grating increase its resolution.

See also: The design was conceived by French physicists Charles Fabry (1867-1945) and Alfred Pérot (1863-1925) in the late nineteenth century; → interferometer.

A type of interferometer wherein the beam of light undergoes multiple reflections between two closely spaced partially silvered surfaces. Part of the light is transmitted each time the light reaches the second surface, resulting in multiple offset beams which can interfere with each other. The large number of interfering rays produces an interferometer with extremely high resolution, somewhat like the multiple slits of a diffraction grating increase its resolution.

See also: The design was conceived by French physicists Charles Fabry (1867-1945) and Alfred Pérot (1863-1925) in the late nineteenth century; → interferometer.

1. To tell invented stories; create fables or stories filled with fantasy.
   

2. To relate an event as a fable.

Etymology (EN): From L. fabulatus perfect passive participle of fabulor, from fabula, → fable.

Etymology (PE): Afsâne-bâftan “to forge fables, stories,”
from afsâné, → fable, + bâftan “to weave, twist, plait,” → texture.

1. To tell invented stories; create fables or stories filled with fantasy.
   

2. To relate an event as a fable.

Etymology (EN): From L. fabulatus perfect passive participle of fabulor, from fabula, → fable.

Etymology (PE): Afsâne-bâftan “to forge fables, stories,”
from afsâné, → fable, + bâftan “to weave, twist, plait,” → texture.

1. To tell invented stories; create fables or stories filled with fantasy.
   

2. To relate an event as a fable.

See also: → fabulate; → -tion.

1. To tell invented stories; create fables or stories filled with fantasy.
   

2. To relate an event as a fable.

See also: → fabulate; → -tion.

1. Almost impossible to believe; incredible.
   

2. Exceptionally good or unusual; marvelous; superb.

See also: → fable; → -ous.

1. Almost impossible to believe; incredible.
   

2. Exceptionally good or unusual; marvelous; superb.

See also: → fable; → -ous.

1. The front part of the head, from the forehead to the chin.
   

2. A plane surface of a geometric solid. The front of something having more than two sides. → interface.

Etymology (EN): M.E., from O.Fr. face, from L. facies “appearance, form; visage, countenance.”

Etymology (PE): Dim “face,” from Av. daēman- “eye,” from dā(y)- “to see,” didāti “sees” (cf. Mod.Pers. didan “to see,” Mid.Pers. ditan “to see, regard, catch sight of, contemplate, experience;” O.Pers. dī- “to see;” Skt. dhī- “to perceive, think, ponder; thought, reflection, meditation,” dādhye; Gk. dedorka “have seen”).
Ru(y), variant rox
“face, surface; aspect; appearance” (Mid.Pers. rôy, rôdh “face;” Av. raoδa- “growth,” in plural form “appearance,” from raod- “to grow, sprout, shoot;” cf. Skt. róha- “rising, height”).

1. The front part of the head, from the forehead to the chin.
   

2. A plane surface of a geometric solid. The front of something having more than two sides. → interface.

Etymology (EN): M.E., from O.Fr. face, from L. facies “appearance, form; visage, countenance.”

Etymology (PE): Dim “face,” from Av. daēman- “eye,” from dā(y)- “to see,” didāti “sees” (cf. Mod.Pers. didan “to see,” Mid.Pers. ditan “to see, regard, catch sight of, contemplate, experience;” O.Pers. dī- “to see;” Skt. dhī- “to perceive, think, ponder; thought, reflection, meditation,” dādhye; Gk. dedorka “have seen”).
Ru(y), variant rox
“face, surface; aspect; appearance” (Mid.Pers. rôy, rôdh “face;” Av. raoδa- “growth,” in plural form “appearance,” from raod- “to grow, sprout, shoot;” cf. Skt. róha- “rising, height”).

An angle formed by any two adjacent edges of a → polyhedron, in contrast to a → dihedral angle.

See also: → face; → angle.

An angle formed by any two adjacent edges of a → polyhedron, in contrast to a → dihedral angle.

See also: → face; → angle.

A → spiral galaxy oriented such that it is viewed from above or below. → edge-on galaxy.

See also: → face; → on-; → galaxy.

A → spiral galaxy oriented such that it is viewed from above or below. → edge-on galaxy.

See also: → face; → on-; → galaxy.

To make easier, render less difficult.

Etymology (EN): From Fr. faciliter “to make easy,” from stem of L. facilis “easy to do,” from facere “to do,” → fact.

Etymology (PE): Âsânidan “to render easy,” from âsân, → easy.

To make easier, render less difficult.

Etymology (EN): From Fr. faciliter “to make easy,” from stem of L. facilis “easy to do,” from facere “to do,” → fact.

Etymology (PE): Âsânidan “to render easy,” from âsân, → easy.

The act or process of facilitating.

See also: → facilitate; → -tion.

The act or process of facilitating.

See also: → facilitate; → -tion.

1. Ease in moving, acting, or doing.
   

   2. Something that facilitates an action or process.
      

   3. A building, room, array of equipment, or a number of such things, designed to serve a particular function (TheFreeDictionary.com).

Etymology (EN): → facile; → -ity.

Etymology (PE): Âsânâk, from âsân “easy,” + relation suffix -âk, as in xorâk, pušâk, dârâk.

1. Ease in moving, acting, or doing.
   

   2. Something that facilitates an action or process.
      

   3. A building, room, array of equipment, or a number of such things, designed to serve a particular function (TheFreeDictionary.com).

Etymology (EN): → facile; → -ity.

Etymology (PE): Âsânâk, from âsân “easy,” + relation suffix -âk, as in xorâk, pušâk, dârâk.

Something that has actual existence; a piece of information presented as having objective reality. → scientific fact.

Etymology (EN): L. factum “event, occurrence,” literally “something done, deed,” from neut. p.p. of facere “to do” (cf. Fr. faire, Sp. hacer), from PIE base *dhe- “to put, to do” (cf. Mod.Pers. dâdan “to give;” O.Pers./Av. dā- “to give, grant, yield,” dadāiti “he gives; puts;” Skt. dadáti “puts, places;” Hitt. dai- “to place;” Gk. tithenai “to put, set, place;” Lith. deti “to put;” Czech diti, Pol. dziac’, Rus. det’ “to hide,” delat’ “to do;” O.H.G. tuon, Ger. tun, O.E. don “to do”).

Etymology (PE): Bâšâ, from bâš + -â agent suffix; bâš, present stem of budan “to be,” from
Mid.Pers. budan, from O.Pers./Av. bav- “to be; become, take place;” Av. buta- perf. ptcpl. pass., bavaiti “becomes”
(cf. Skt. bhavati “becomes, happens,” bhavah “becoming; condition, state;” PIE *bheu- “to be, come into being, become;”
Gk. phu- “become,” phuein “to bring forth, make grow;” L. fui “I was” (perf. tense of esse), futurus “that is to be, future;” Ger. present first and second person sing. bin, bist; E. to be; Lith. bu’ti “to be;” Rus. byt’ “to be”); budé also from budan.

Something that has actual existence; a piece of information presented as having objective reality. → scientific fact.

Etymology (EN): L. factum “event, occurrence,” literally “something done, deed,” from neut. p.p. of facere “to do” (cf. Fr. faire, Sp. hacer), from PIE base *dhe- “to put, to do” (cf. Mod.Pers. dâdan “to give;” O.Pers./Av. dā- “to give, grant, yield,” dadāiti “he gives; puts;” Skt. dadáti “puts, places;” Hitt. dai- “to place;” Gk. tithenai “to put, set, place;” Lith. deti “to put;” Czech diti, Pol. dziac’, Rus. det’ “to hide,” delat’ “to do;” O.H.G. tuon, Ger. tun, O.E. don “to do”).

Etymology (PE): Bâšâ, from bâš + -â agent suffix; bâš, present stem of budan “to be,” from
Mid.Pers. budan, from O.Pers./Av. bav- “to be; become, take place;” Av. buta- perf. ptcpl. pass., bavaiti “becomes”
(cf. Skt. bhavati “becomes, happens,” bhavah “becoming; condition, state;” PIE *bheu- “to be, come into being, become;”
Gk. phu- “become,” phuein “to bring forth, make grow;” L. fui “I was” (perf. tense of esse), futurus “that is to be, future;” Ger. present first and second person sing. bin, bist; E. to be; Lith. bu’ti “to be;” Rus. byt’ “to be”); budé also from budan.

1. One that actively contributes to the production of a result.
   

2. Math.: Any of the numbers or symbols that when multiplied together form a → product.

Etymology (EN): M.Fr. facteur “agent, representative,” from L. factor
“doer or maker,” from facere “to do” (cf. Fr. faire, Sp. hacer); from PIE base *dhe- “to put, to do;” cf. Skt. dadhati “puts, places;” Av. dadaiti “he puts;”
Hitt. dai- “to place;” Gk. tithenai “to put, set, place;” Lith. deti “to put;” Rus. det’ “to hide,” delat’ “to do;” O.H.G. tuon; Ger. tun; O.S., O.E. don “to do.”

Etymology (PE): Karvand, from kar- root of Mod.Pers. verb kardan “to do, to make” (Mid.Pers. kardan; O.Pers./Av. kar- “to do, make, build;” Av. kərənaoiti “he makes;” cf. Skt. kr- “to do, to make,” krnoti “he makes, he does,” karoti “he makes, he does,” karma “act, deed;” PIE base k^wer- “to do, to make”)

• -vand a suffix forming adjectives and agent nouns.

1. One that actively contributes to the production of a result.
   

2. Math.: Any of the numbers or symbols that when multiplied together form a → product.

Etymology (EN): M.Fr. facteur “agent, representative,” from L. factor
“doer or maker,” from facere “to do” (cf. Fr. faire, Sp. hacer); from PIE base *dhe- “to put, to do;” cf. Skt. dadhati “puts, places;” Av. dadaiti “he puts;”
Hitt. dai- “to place;” Gk. tithenai “to put, set, place;” Lith. deti “to put;” Rus. det’ “to hide,” delat’ “to do;” O.H.G. tuon; Ger. tun; O.S., O.E. don “to do.”

Etymology (PE): Karvand, from kar- root of Mod.Pers. verb kardan “to do, to make” (Mid.Pers. kardan; O.Pers./Av. kar- “to do, make, build;” Av. kərənaoiti “he makes;” cf. Skt. kr- “to do, to make,” krnoti “he makes, he does,” karoti “he makes, he does,” karma “act, deed;” PIE base k^wer- “to do, to make”)

• -vand a suffix forming adjectives and agent nouns.

A diagram representing a systematic way of determining all the prime factors of a number.

See also: → factor; → tree.

A diagram representing a systematic way of determining all the prime factors of a number.

See also: → factor; → tree.

1. (n.) The product of all the positive integers from 1 to n, denoted by symbol n!
   
2. (adj.) of or pertaining to factors or factorials.

See also: → factor + -ial, from L. -alis,
→ -al.

1. (n.) The product of all the positive integers from 1 to n, denoted by symbol n!
   
2. (adj.) of or pertaining to factors or factorials.

See also: → factor + -ial, from L. -alis,
→ -al.

The operation of resolving a quantity into factors.

See also: → factor + → -ize.

The operation of resolving a quantity into factors.

See also: → factor + → -ize.

A bright area of the → photosphere of the Sun visible in white light and best seen near the solar limb, although they occur all across the Sun. Faculae raise several hundred kilometers above the photosphere and are associated with → sunspots. They often appear immediately before the formation of a sunspot group and remain visible for several days or weeks after the disappearance of the spots. Faculae are formed when a strong magnetic field heats a region of the photosphere to higher temperatures than the surrounding area.

Etymology (EN): Facula, from L. fac-, fax “torch” + -ula, → -ule.

Etymology (PE): Perisk, periska, biriske in Lori, Laki, and Kurd. dialects “spark” (Lârestâni pelita), probably related to Lori porpor “blazing charcoal,” Gilaki bur, biur “smokeless red fire;” cf. Tokharian por, puwar “fire;” Gk. pyr “fire;” Hitt. pahhur “fire;” Skt. pū- “to cleanse;” E. fire; O..E. fyr, from P.Gmc. *fuir (cf. O.N. fürr, M.Du. vuur, Ger. Feuer); PIE base *paewr- “fire.”

A bright area of the → photosphere of the Sun visible in white light and best seen near the solar limb, although they occur all across the Sun. Faculae raise several hundred kilometers above the photosphere and are associated with → sunspots. They often appear immediately before the formation of a sunspot group and remain visible for several days or weeks after the disappearance of the spots. Faculae are formed when a strong magnetic field heats a region of the photosphere to higher temperatures than the surrounding area.

Etymology (EN): Facula, from L. fac-, fax “torch” + -ula, → -ule.

Etymology (PE): Perisk, periska, biriske in Lori, Laki, and Kurd. dialects “spark” (Lârestâni pelita), probably related to Lori porpor “blazing charcoal,” Gilaki bur, biur “smokeless red fire;” cf. Tokharian por, puwar “fire;” Gk. pyr “fire;” Hitt. pahhur “fire;” Skt. pū- “to cleanse;” E. fire; O..E. fyr, from P.Gmc. *fuir (cf. O.N. fürr, M.Du. vuur, Ger. Feuer); PIE base *paewr- “fire.”

A temperature scale (°F) in which the → freezing point of → water is 32 degrees and the → boiling point is 212 degrees; the points are placed
180 degrees apart. It converts to the → Celsius scale by the formula: C = (5/9)(F - 32). See also → Kelvin scale, → Rankine scale, → Reaumur scale.

See also: Developed by the German physicist Gabriel Fahrenheit (1686-1736); → scale.

A temperature scale (°F) in which the → freezing point of → water is 32 degrees and the → boiling point is 212 degrees; the points are placed
180 degrees apart. It converts to the → Celsius scale by the formula: C = (5/9)(F - 32). See also → Kelvin scale, → Rankine scale, → Reaumur scale.

See also: Developed by the German physicist Gabriel Fahrenheit (1686-1736); → scale.

1. To be unsuccessful in achieving something expected, attempted, or desired.
   

   2. To neglect to do something.
      

   3. To be e unsuccessful in an examination.

Etymology (EN): M.E. failen, from O.Fr. falir “be lacking, miss, not succeed; come to an end; make a mistake; be dying,” from Vulgar L. *fallire, from L. fallere “to trip, cause to fall;” figuratively “to deceive, trick, dupe, cheat; fail, be lacking or defective.”

Etymology (PE): Qâvidan, from Choresmian γaw “to fail, to commit a fault;” cf. Av. gau- “to commit a sin;” Parthian (+*fra-) pargaw- “to owe, to lack;” Ossetian qaewyn/qyd “to be in need of something, to lack;” Proto-Ir. *gaHu- “to be faulty, wanting; to need;” PIE *g^heH<SUB2u- “to be faulty, lacking, insufficient;” cf. Old L. hauelod “insufficient, false,” L. hau(d) “not;” O.Irish gáu, gó; Welsh gau “lie” (Cheung 2007).

1. To be unsuccessful in achieving something expected, attempted, or desired.
   

   2. To neglect to do something.
      

   3. To be e unsuccessful in an examination.

Etymology (EN): M.E. failen, from O.Fr. falir “be lacking, miss, not succeed; come to an end; make a mistake; be dying,” from Vulgar L. *fallire, from L. fallere “to trip, cause to fall;” figuratively “to deceive, trick, dupe, cheat; fail, be lacking or defective.”

Etymology (PE): Qâvidan, from Choresmian γaw “to fail, to commit a fault;” cf. Av. gau- “to commit a sin;” Parthian (+*fra-) pargaw- “to owe, to lack;” Ossetian qaewyn/qyd “to be in need of something, to lack;” Proto-Ir. *gaHu- “to be faulty, wanting; to need;” PIE *g^heH<SUB2u- “to be faulty, lacking, insufficient;” cf. Old L. hauelod “insufficient, false,” L. hau(d) “not;” O.Irish gáu, gó; Welsh gau “lie” (Cheung 2007).

1. An act or instance of failing; lack of success.
   

   2. A state of inability to perform a normal function.

See also: Verbal noun from → fail.

1. An act or instance of failing; lack of success.
   

   2. A state of inability to perform a normal function.

See also: Verbal noun from → fail.

1. Lacking brightness, vividness, clearness, loudness, strength; feeble; exhausted.
   

   2. To lose consciousness temporarily; to lose brightness (Dictionary.com).

Etymology (EN): From O.Fr. faint, feint “false, deceitful; sham, artificial; weak, faint, lazy,” p.p. of feindre “hesitate, falter, show weakness,” from L. fingere “to touch, handle; change.”

Etymology (PE): Tâm, from Pers. tâm “feeble, fragile, weak,” ultimately from Proto-Ir. *tamH- “to faint, be tired;” cf. Khotanese ttām&#257 “fatigue;” Parthian t’m’dg “fainted, choking;” Gilak (Langarudi) tâmâ, tâm “silent;” PIE base *temH- “to faint, to be dark;” tâmidan, infinitive from tâm.
Nazâr, from Mid.Pers. nizâr “weak, feeble” (variant zâr), zarmân “old man, deterioration;” Av. zairina- “exhausting, slackening,” zaurura- “weak through old age, decrepit;” cf. Skt. jára- “wearing out, exhaustion,” jaranā- “old, decayed,” jarimán- “weakness through old age,” Gk. geron “old man,” L. granum “grain;” PIE base *ger- “wear away.”
Kamtâb, from kam “little, few; deficient, wanting; scarce,” from Mid.Pers. kam “little, small, few,” O.Pers./Av. kamna- “small, few”

• tâb “light; heat, warmth; illuminating,” from tâbidan, tâftan “to shine,” tafsidan “to become hot;” Av. tāp-, taf- “to warm up, heat,” tafsat “became hot,” tāpaiieiti “to create warmth;” cf.
  Skt. tap- “to spoil, injure, damage; to suffer; to heat, be/become hot,” tapati “burns;” L. tepere “to be warm,” tepidus “warm;” PIE base *tep- “warm.”
  Kamnur, from kam, as above, + nur, → light.

1. Lacking brightness, vividness, clearness, loudness, strength; feeble; exhausted.
   

   2. To lose consciousness temporarily; to lose brightness (Dictionary.com).

Etymology (EN): From O.Fr. faint, feint “false, deceitful; sham, artificial; weak, faint, lazy,” p.p. of feindre “hesitate, falter, show weakness,” from L. fingere “to touch, handle; change.”

Etymology (PE): Tâm, from Pers. tâm “feeble, fragile, weak,” ultimately from Proto-Ir. *tamH- “to faint, be tired;” cf. Khotanese ttām&#257 “fatigue;” Parthian t’m’dg “fainted, choking;” Gilak (Langarudi) tâmâ, tâm “silent;” PIE base *temH- “to faint, to be dark;” tâmidan, infinitive from tâm.
Nazâr, from Mid.Pers. nizâr “weak, feeble” (variant zâr), zarmân “old man, deterioration;” Av. zairina- “exhausting, slackening,” zaurura- “weak through old age, decrepit;” cf. Skt. jára- “wearing out, exhaustion,” jaranā- “old, decayed,” jarimán- “weakness through old age,” Gk. geron “old man,” L. granum “grain;” PIE base *ger- “wear away.”
Kamtâb, from kam “little, few; deficient, wanting; scarce,” from Mid.Pers. kam “little, small, few,” O.Pers./Av. kamna- “small, few”

• tâb “light; heat, warmth; illuminating,” from tâbidan, tâftan “to shine,” tafsidan “to become hot;” Av. tāp-, taf- “to warm up, heat,” tafsat “became hot,” tāpaiieiti “to create warmth;” cf.
  Skt. tap- “to spoil, injure, damage; to suffer; to heat, be/become hot,” tapati “burns;” L. tepere “to be warm,” tepidus “warm;” PIE base *tep- “warm.”
  Kamnur, from kam, as above, + nur, → light.

The contradiction between a colder Sun (about 30% less luminous) some 4 billion years ago, as predicted by models, and the warm ancient Terrestrial and Martian climates derived from geological evidence.

See also: → faint; → early; → sun; → paradox.

The contradiction between a colder Sun (about 30% less luminous) some 4 billion years ago, as predicted by models, and the warm ancient Terrestrial and Martian climates derived from geological evidence.

See also: → faint; → early; → sun; → paradox.

For unaided eye, a star of visual magnitude around 5-6. Otherwise, on an image, a star that has a lesser brightness compared to others of the same field.

See also: → faint; → star.

For unaided eye, a star of visual magnitude around 5-6. Otherwise, on an image, a star that has a lesser brightness compared to others of the same field.

See also: → faint; → star.

1. Confidence or trust in a person or thing.
   

   2. Belief that is not based on proof.
      

   3. A system of religious belief (Dictionary.com).

Etymology (EN): M.E. feith fei, fai “faithfulness to a trust or promise; loyalty to a person; honesty, truthfulness,” from Anglo-Fr. and O.Fr. feid, foi “faith, belief, trust, confidence; pledge,” from L. fides “trust, faith, confidence, reliance, credence, belief,” from root of fidere “to trust,“from PIE root *bheidh- “to trust, confide, persuade.”

Etymology (PE): Imân, loan from Ar. al-imân “faith, belief, trust.”

1. Confidence or trust in a person or thing.
   

   2. Belief that is not based on proof.
      

   3. A system of religious belief (Dictionary.com).

Etymology (EN): M.E. feith fei, fai “faithfulness to a trust or promise; loyalty to a person; honesty, truthfulness,” from Anglo-Fr. and O.Fr. feid, foi “faith, belief, trust, confidence; pledge,” from L. fides “trust, faith, confidence, reliance, credence, belief,” from root of fidere “to trust,“from PIE root *bheidh- “to trust, confide, persuade.”

Etymology (PE): Imân, loan from Ar. al-imân “faith, belief, trust.”

1. Something that is not what it seems to be; counterfeit.
   

   2. To forge or counterfeit; pretend.

Etymology (EN): Of unknown origin.

Etymology (PE): Mâx (Dehxodâ) “counterfeit, not genuine, forged, adulterated (gold or silver);” Mid.Pes. mih “false; contrary;” Av. maēθā- “deviating; changeable,” miθō “falsely, wrongly;” maybe related to mâz “a wrinkle, twist, fold;” (Khonsâri, Natanz-Toroqi) max “unstable, volatile.”

1. Something that is not what it seems to be; counterfeit.
   

   2. To forge or counterfeit; pretend.

Etymology (EN): Of unknown origin.

Etymology (PE): Mâx (Dehxodâ) “counterfeit, not genuine, forged, adulterated (gold or silver);” Mid.Pes. mih “false; contrary;” Av. maēθā- “deviating; changeable,” miθō “falsely, wrongly;” maybe related to mâz “a wrinkle, twist, fold;” (Khonsâri, Natanz-Toroqi) max “unstable, volatile.”

A collected meteorite whose arrival on Earth is witnessed, as opposed to a → find.

Etymology (EN): M.E. fallen, from O.E. feallan, from P.Gmc. *fallanan (cf. O.N. falla, O.H.G. fallan), from PIE base *phol- “to fall” (cf. Arm. p’ul “downfall;” Lith. puola “to fall”).

Etymology (PE): Oft, stem of oftâdan “to fall;” Mid.Pers. opastan “to fall,” patet “falls;” Av. pat- " to fly, fall, rush," patarəta- “winged;” cf. Skt. patati “he flies, falls,” pátra- “wing, feather, leaf;” Gk. piptein “to fall,” pterux “wing;” L. penna “feather, wing;” O.E. feðer “feather;” PIE base *pet- “to fly, rush.”

A collected meteorite whose arrival on Earth is witnessed, as opposed to a → find.

Etymology (EN): M.E. fallen, from O.E. feallan, from P.Gmc. *fallanan (cf. O.N. falla, O.H.G. fallan), from PIE base *phol- “to fall” (cf. Arm. p’ul “downfall;” Lith. puola “to fall”).

Etymology (PE): Oft, stem of oftâdan “to fall;” Mid.Pers. opastan “to fall,” patet “falls;” Av. pat- " to fly, fall, rush," patarəta- “winged;” cf. Skt. patati “he flies, falls,” pátra- “wing, feather, leaf;” Gk. piptein “to fall,” pterux “wing;” L. penna “feather, wing;” O.E. feðer “feather;” PIE base *pet- “to fly, rush.”

Logic: An → error in → reasoning that renders an → argument logically → invalid such as affirming the → consequent and → denying the → antecedent.

Etymology (EN): From L. fallacia “deception,” from fallere
“to deceive, trick, cheat; fail, be defective.”

Etymology (PE): Titâl (Dehxodâ) “deceit; deceiving speech, fallacious words;” cf. Tabari titâl hâ kərdan “to deceive (somebody) wheedlingly,” Pashtu titâl “duplicity, guile, deceit, fraud.”

Logic: An → error in → reasoning that renders an → argument logically → invalid such as affirming the → consequent and → denying the → antecedent.

Etymology (EN): From L. fallacia “deception,” from fallere
“to deceive, trick, cheat; fail, be defective.”

Etymology (PE): Titâl (Dehxodâ) “deceit; deceiving speech, fallacious words;” cf. Tabari titâl hâ kərdan “to deceive (somebody) wheedlingly,” Pashtu titâl “duplicity, guile, deceit, fraud.”

1. Not true or correct; erroneous.
   
2. Not properly, accurately, or honestly made, done, or adjusted.
   → false color, → false dawn, → false nucleus, → false vacuum.

Etymology (EN): From O.Fr. fals, faus, from L. falsus “deceived, erroneous, mistaken,” p.p. of fallere “to deceive, disappoint.”

Etymology (PE): Zif, from Tâleši saf “wrong,” from Mid.Pers. zêfân, zaspân “wrong, vile;” in classical Pers. dictionaries zif “churlishness; sin.”

1. Not true or correct; erroneous.
   
2. Not properly, accurately, or honestly made, done, or adjusted.
   → false color, → false dawn, → false nucleus, → false vacuum.

Etymology (EN): From O.Fr. fals, faus, from L. falsus “deceived, erroneous, mistaken,” p.p. of fallere “to deceive, disappoint.”

Etymology (PE): Zif, from Tâleši saf “wrong,” from Mid.Pers. zêfân, zaspân “wrong, vile;” in classical Pers. dictionaries zif “churlishness; sin.”

In imaging technique, assigning color to black and white images to differentiate features or convey information. → true color.

See also: → false; → color.

In imaging technique, assigning color to black and white images to differentiate features or convey information. → true color.

See also: → false; → color.

An unusually early glow of the horizon near the rising sun during certain times of the year. This early glow does not originate directly from the Sun, but is rather caused by → zodiacal light. It may be mistaken for a sunrise.

See also: → false; → dawn.

An unusually early glow of the horizon near the rising sun during certain times of the year. This early glow does not originate directly from the Sun, but is rather caused by → zodiacal light. It may be mistaken for a sunrise.

See also: → false; → dawn.

An especially concentrated region in the → coma of some → comets, representing the dense cloud of inner coma rather than the much smaller true nucleus. Also called apparent nucleus and → pseudo-nucleus.

See also: → false; → nucleus.

An especially concentrated region in the → coma of some → comets, representing the dense cloud of inner coma rather than the much smaller true nucleus. Also called apparent nucleus and → pseudo-nucleus.

See also: → false; → nucleus.

A peculiar, hypothetical state of matter which is predicted to exist by current theories of → elementary particles, including the → grand unified theories. Unlike the ordinary vacuum, a false vacuum has a large → energy density and a large → negative pressure. A false vacuum is the driving force behind the rapid expansion in the → inflationary model of the → Universe.

See also: → false; → vacuum.

A peculiar, hypothetical state of matter which is predicted to exist by current theories of → elementary particles, including the → grand unified theories. Unlike the ordinary vacuum, a false vacuum has a large → energy density and a large → negative pressure. A false vacuum is the driving force behind the rapid expansion in the → inflationary model of the → Universe.

See also: → false; → vacuum.

Philosophy of science: The concept according to which a proposition or theory cannot be scientific if it does not admit consideration of the possibility of its being false. According to Karl Popper (1902-1994), falsifiability is the crucial feature of scientific hypotheses. Any theory not falsifiable is said to be unscientific.

See also: → falsifiable; → -ity.

Philosophy of science: The concept according to which a proposition or theory cannot be scientific if it does not admit consideration of the possibility of its being false. According to Karl Popper (1902-1994), falsifiability is the crucial feature of scientific hypotheses. Any theory not falsifiable is said to be unscientific.

See also: → falsifiable; → -ity.

The quality of something that can be falsified. → falsifiability.

See also: → falsify; → -able.

The quality of something that can be falsified. → falsifiability.

See also: → falsify; → -able.

1. To show or prove that a theory is incorrect or false.
   

2. To alter something in order to deceive.

See also: Verb from → false.

1. To show or prove that a theory is incorrect or false.
   

2. To alter something in order to deceive.

See also: Verb from → false.

The quality or condition of being → false. Opposite of → truth.

See also: → false; → -ity.

The quality or condition of being → false. Opposite of → truth.

See also: → false; → -ity.

A group of entities with similar properties and common origin.

→ family of curves, → family of distributions, → family of sets, → comet family.

Etymology (EN): From L. familia “household, the slaves of a household,” from famulus “servant,” of unknown origin.

Etymology (PE): Xânevâdé “family,” from xâné “house, home, houshold”

• vâdé “root, foundation, origin.” Xâné, from Mid.Pers. xânak, xân, xôn; cf. L. cunae “cradle;” Gk. kome “village;” Pers. Aftari dialect kiye “house, home;” PIE base *kei- “bed; to lie, to settle; beloved” (other cognates: P.Gmc. *khaim-; O.E. ham “dwelling, house, village;” E. home; Ger. Heim; L. civis “townsman;” Fr. cité; E. city; Skt. śiva- “auspicious, dear”).

A group of entities with similar properties and common origin.

→ family of curves, → family of distributions, → family of sets, → comet family.

Etymology (EN): From L. familia “household, the slaves of a household,” from famulus “servant,” of unknown origin.

Etymology (PE): Xânevâdé “family,” from xâné “house, home, houshold”

• vâdé “root, foundation, origin.” Xâné, from Mid.Pers. xânak, xân, xôn; cf. L. cunae “cradle;” Gk. kome “village;” Pers. Aftari dialect kiye “house, home;” PIE base *kei- “bed; to lie, to settle; beloved” (other cognates: P.Gmc. *khaim-; O.E. ham “dwelling, house, village;” E. home; Ger. Heim; L. civis “townsman;” Fr. cité; E. city; Skt. śiva- “auspicious, dear”).

A set of similar curves which are distinguished by the values taken by one or more parameters in their general equation. For example, the general solution of a differential equation is represented by a family of curves.

See also: → family; → curve.

A set of similar curves which are distinguished by the values taken by one or more parameters in their general equation. For example, the general solution of a differential equation is represented by a family of curves.

See also: → family; → curve.

A set of distributions which have the same general mathematical → formula.

See also: → family; → distribution.

A set of distributions which have the same general mathematical → formula.

See also: → family; → distribution.

A → collection of → subsets of a set.

See also: → family; → set.

A → collection of → subsets of a set.

See also: → family; → set.

In 3D → magnetic reconnection models of solar plasma, a plane or curve surface composed of magnetic field lines emanating from the → magnetic null point (almost radially in the absence of electric currents and spirally if electric currents are present). See also → spine (Lau & Finn. 1990, ApJ 350, 672; Parnell et al. 1996, Physics of Plasmas 3, 759).

Etymology (EN): M.E., from O.E. fann, from L. vannus “a basket or shovel for winnowing grain,” related to ventus, → wind.

Etymology (PE): Bâdzan “fan, ventilator,” from bâd, → wind + zan from zadan “to strike, beat; to play an instrument; to do” (Mid.Pers. zatan, žatan; O.Pers./Av. jan-, gan- “to strike, hit, smite, kill” (jantar- “smiter”); cf.
Skt. han- “to strike, beat” (hantar- “smiter, killer”);
Gk. theinein “to strike;” L. fendere “to strike, push;” Gmc. *gundjo “war, battle;” PIE *g^when- “to strike, kill”).

In 3D → magnetic reconnection models of solar plasma, a plane or curve surface composed of magnetic field lines emanating from the → magnetic null point (almost radially in the absence of electric currents and spirally if electric currents are present). See also → spine (Lau & Finn. 1990, ApJ 350, 672; Parnell et al. 1996, Physics of Plasmas 3, 759).

Etymology (EN): M.E., from O.E. fann, from L. vannus “a basket or shovel for winnowing grain,” related to ventus, → wind.

Etymology (PE): Bâdzan “fan, ventilator,” from bâd, → wind + zan from zadan “to strike, beat; to play an instrument; to do” (Mid.Pers. zatan, žatan; O.Pers./Av. jan-, gan- “to strike, hit, smite, kill” (jantar- “smiter”); cf.
Skt. han- “to strike, beat” (hantar- “smiter, killer”);
Gk. theinein “to strike;” L. fendere “to strike, push;” Gmc. *gundjo “war, battle;” PIE *g^when- “to strike, kill”).

In the → Fanaroff-Riley classification, sources with R_FR < 0.5. Fanaroff and Riley (1974) found that nearly all sources with luminosity L(178MHz) ≤ 2 × 10²⁵h₁₀₀^-2 W Hz^-1 sr^-1 were of class I. FR-I → radio jets are thought to be → subsonic, possibly due to mass entrainment, which makes them amenable to distortions in the interaction with the ambient medium.

See also: → Fanaroff-Riley classification; → class.

In the → Fanaroff-Riley classification, sources with R_FR < 0.5. Fanaroff and Riley (1974) found that nearly all sources with luminosity L(178MHz) ≤ 2 × 10²⁵h₁₀₀^-2 W Hz^-1 sr^-1 were of class I. FR-I → radio jets are thought to be → subsonic, possibly due to mass entrainment, which makes them amenable to distortions in the interaction with the ambient medium.

See also: → Fanaroff-Riley classification; → class.

In the → Fanaroff-Riley classification, → radio sources with hotspots in their lobes at distances from the center which are such that R_FR > 0.5. The → radio jets in FR-II sources are expected to be highly → supersonic, allowing them to travel large distances.

See also: → Fanaroff-Riley classification; → class.

In the → Fanaroff-Riley classification, → radio sources with hotspots in their lobes at distances from the center which are such that R_FR > 0.5. The → radio jets in FR-II sources are expected to be highly → supersonic, allowing them to travel large distances.

See also: → Fanaroff-Riley classification; → class.

A classification scheme for distinguishing a → radio galaxy from an → active galaxy based on their → radio frequency  and → luminosity and their kpc-scale appearance. Analyzing a sample of 57 radio galaxies from the → 3CR catalogue, which were clearly resolved at 1.4 GHz or 5 GHz, Fanaroff & Riley (1974) discovered that the relative positions of regions of high and low → surface brightness in the → lobes of extragalactic → radio sources are correlated with their radio luminosity. They divided the sample into two classes using the ratio R_FR of the distance between the regions of highest surface brightness on opposite sides of the central galaxy or quasar, to the total extent of the source up to the lowest brightness contour in the map. → Fanaroff-Riley Class I (FR-I) , → Fanaroff-Riley Class II (FR-II). The boundary between the two classes is not very sharp, and there is some overlap in the luminosities of sources classified as FR-I or FR-II on the basis of their structures. The physical cause of the FR-I/II dichotomy probably lies in the type of flow in the → radio jets.

See also: Bernard L. Fanaroff and Julia M. Riley, 1974, MNRAS 167, 31P; → classification.

A classification scheme for distinguishing a → radio galaxy from an → active galaxy based on their → radio frequency  and → luminosity and their kpc-scale appearance. Analyzing a sample of 57 radio galaxies from the → 3CR catalogue, which were clearly resolved at 1.4 GHz or 5 GHz, Fanaroff & Riley (1974) discovered that the relative positions of regions of high and low → surface brightness in the → lobes of extragalactic → radio sources are correlated with their radio luminosity. They divided the sample into two classes using the ratio R_FR of the distance between the regions of highest surface brightness on opposite sides of the central galaxy or quasar, to the total extent of the source up to the lowest brightness contour in the map. → Fanaroff-Riley Class I (FR-I) , → Fanaroff-Riley Class II (FR-II). The boundary between the two classes is not very sharp, and there is some overlap in the luminosities of sources classified as FR-I or FR-II on the basis of their structures. The physical cause of the FR-I/II dichotomy probably lies in the type of flow in the → radio jets.

See also: Bernard L. Fanaroff and Julia M. Riley, 1974, MNRAS 167, 31P; → classification.

Being at a great distance; remote in time or place.

Etymology (EN): O.E. feorr “to a great distance, long ago,” from P.Gmc. *ferro (cf. Du. ver, Ger. fern), from PIE *per- “through, across, beyond” (cf. O.Pers. para “on the other side (of);” Av. parə “beyond, more than, superior,” parô “except,” pərətu- “crossing, bridge;” Mod.Pers. pol “bridge;”
Skt. parás “far, further, beyond,” Gk. pera “across, beyond,” L. per “through”).

Etymology (PE): Dur, from Mid.Pers. dūr “far, distant, remote;” O.Pers. dūra- “far (in time or space),” dūraiy “afar, far away, far and wide;” Av. dūra-, dūirē “far,” from dav- “to move away;” cf. Skt. dūrá- “far; distance (in space and time);” PIE base *deu- “to move forward, pass;” cf. Gk. den “for a long time,” deros “lasting long.”

Being at a great distance; remote in time or place.

Etymology (EN): O.E. feorr “to a great distance, long ago,” from P.Gmc. *ferro (cf. Du. ver, Ger. fern), from PIE *per- “through, across, beyond” (cf. O.Pers. para “on the other side (of);” Av. parə “beyond, more than, superior,” parô “except,” pərətu- “crossing, bridge;” Mod.Pers. pol “bridge;”
Skt. parás “far, further, beyond,” Gk. pera “across, beyond,” L. per “through”).

Etymology (PE): Dur, from Mid.Pers. dūr “far, distant, remote;” O.Pers. dūra- “far (in time or space),” dūraiy “afar, far away, far and wide;” Av. dūra-, dūirē “far,” from dav- “to move away;” cf. Skt. dūrá- “far; distance (in space and time);” PIE base *deu- “to move forward, pass;” cf. Gk. den “for a long time,” deros “lasting long.”

Infrared radiation in the wavelength range (25-40) to (200-350) microns emitted by cold molecular/dust clouds.

See also: → far; → infrared.

Infrared radiation in the wavelength range (25-40) to (200-350) microns emitted by cold molecular/dust clouds.

See also: → far; → infrared.

Ultraviolet radiation in the wavelength range 912-2000 Å. See also → extreme ultraviolet.

See also: → far; → ultraviolet.

Ultraviolet radiation in the wavelength range 912-2000 Å. See also → extreme ultraviolet.

See also: → far; → ultraviolet.

The portion of the → electromagnetic radiation in the wavelength range between about 30 and 300 → microns. See also: → infrared radiation, → near-infrared, → mid-infrared, → submillimeter radiation.

See also: → far; → infrared.

The portion of the → electromagnetic radiation in the wavelength range between about 30 and 300 → microns. See also: → infrared radiation, → near-infrared, → mid-infrared, → submillimeter radiation.

See also: → far; → infrared.

The → SI unit of → capacitance,
defined as the capacitance of a conductor whose → potential
increases by one → volt when a charge of 1 → coulomb is imparted to it; symbol F.

See also: Named after the British physicist Michael Faraday (1791-1867), who made several major contributions to the fields of electricity and magnetism.

The → SI unit of → capacitance,
defined as the capacitance of a conductor whose → potential
increases by one → volt when a charge of 1 → coulomb is imparted to it; symbol F.

See also: Named after the British physicist Michael Faraday (1791-1867), who made several major contributions to the fields of electricity and magnetism.

An enclosure made of conducting material, such as wire mesh or metal plates, that shields what it contains from external electric fields. According to → Gauss’s theorem, the electric field inside a hollow conductor is nil. In order to demonstrate this, Faraday, in 1836, made a large box covered with wire mesh, and went inside it himself with an → electroscope. Powerful charges were applied to the outside of the box, but he detected no effect inside the cage.

See also: → farad; → cage.

An enclosure made of conducting material, such as wire mesh or metal plates, that shields what it contains from external electric fields. According to → Gauss’s theorem, the electric field inside a hollow conductor is nil. In order to demonstrate this, Faraday, in 1836, made a large box covered with wire mesh, and went inside it himself with an → electroscope. Powerful charges were applied to the outside of the box, but he detected no effect inside the cage.

See also: → farad; → cage.

Same as → Faraday rotation.

See also: → farad; → effect.

Same as → Faraday rotation.

See also: → farad; → effect.

The rotation of the plane of → polarization experienced by a beam of → linearly polarized radiation when the radiation passes through a material containing a magnetic field with a component in the direction of propagation. This effect occurs in → H II regions in which a magnetic field causes a change in the polarized waves passing through. Same as → Faraday effect.

See also: → farad; → rotation.

The rotation of the plane of → polarization experienced by a beam of → linearly polarized radiation when the radiation passes through a material containing a magnetic field with a component in the direction of propagation. This effect occurs in → H II regions in which a magnetic field causes a change in the polarized waves passing through. Same as → Faraday effect.

See also: → farad; → rotation.

The induced → electromotive force in a circuit is equal in magnitude and opposite in sign to the rate of change of the → magnetic flux through the surface bounded by the circuit. Mathematically, it is expressed as: ∇ x E = -∂B/∂t, which is one of the four → Maxwell’s equations.

See also: → farad; → law; → induction.

The induced → electromotive force in a circuit is equal in magnitude and opposite in sign to the rate of change of the → magnetic flux through the surface bounded by the circuit. Mathematically, it is expressed as: ∇ x E = -∂B/∂t, which is one of the four → Maxwell’s equations.

See also: → farad; → law; → induction.

An area of land devoted to the raising of animals, fish, plants, etc.

Etymology (EN): M.E. ferme “lease, rented land, rent,” from O.Fr., from Vulgar L. *ferma, derivative of *fermare for L. firmare “to make firm, confirm.”

Etymology (PE): Keštzâr “farm, field,” from kešt past stem of keštan, variants kâštan, kâridan “to cultivate, to plant;” Mid.Pers. kištan, kâridan “to sow, plant; to make furrows;” Av. kar- “to strew seed, cultivate,” kāraiieiti “cultivates;” cf. Skt. kar- “to scatter, strew, pour out,” + suffix -zâr denoting profusion, abundance, as in kârzâr “a field of battle; combat” šurezâr “unfertile, salty ground; nitrous earth,” xoškzâr “arid land,” and so forth.

An area of land devoted to the raising of animals, fish, plants, etc.

Etymology (EN): M.E. ferme “lease, rented land, rent,” from O.Fr., from Vulgar L. *ferma, derivative of *fermare for L. firmare “to make firm, confirm.”

Etymology (PE): Keštzâr “farm, field,” from kešt past stem of keštan, variants kâštan, kâridan “to cultivate, to plant;” Mid.Pers. kištan, kâridan “to sow, plant; to make furrows;” Av. kar- “to strew seed, cultivate,” kāraiieiti “cultivates;” cf. Skt. kar- “to scatter, strew, pour out,” + suffix -zâr denoting profusion, abundance, as in kârzâr “a field of battle; combat” šurezâr “unfertile, salty ground; nitrous earth,” xoškzâr “arid land,” and so forth.

Moving or able to move, operate, function, or take effect quickly; quick; swift; rapid (Dictionary.com).

Etymology (EN): M.E., from O.E. fæst “firmly fixed, steadfast;” O.Fr. fest, O.N. fastr, Du. vast, Ger. fest.

Etymology (PE): Tond “swift, rapid, brisk; fierce, severe,” → velocity.

Moving or able to move, operate, function, or take effect quickly; quick; swift; rapid (Dictionary.com).

Etymology (EN): M.E., from O.E. fæst “firmly fixed, steadfast;” O.Fr. fest, O.N. fastr, Du. vast, Ger. fest.

Etymology (PE): Tond “swift, rapid, brisk; fierce, severe,” → velocity.

A bright → burst of → radio emission lasting only a few milliseconds, and thought to be of → extragalactic origin. The first ever detected such burst, called the → Lorimer burst, was in 2007. It lasted only 5 milliseconds, but the single radio → pulse was dispersed over a wide range of frequencies (→ dispersion measure). This suggested a → cosmic origin for the burst, because the radiation must have passed through very distant → intergalactic clouds to be so highly dispersed. The second FRB was detected in 2012 in archival data from the Parkes Radio Telescope, the same telescope through which the original burst was seen. No temporally coincident → X-ray or → gamma ray signature was identified in association with the bursts. Most recent results suggest FRBs as a new population of explosive events at cosmological distances of up to 3 → giga  → parsecs, that is → redshifts of 0.5 to 1. While physical interpretations for this phenomenon remain speculative, they are thought to involve highly → compact objects, such as → neutron stars. See also → blitzar.

See also: The term fast radio burst was coined by Thornton et al., 2013, Science, 341, 53 (arXiv:1307.1628); → fast; → radio; → burst.

A bright → burst of → radio emission lasting only a few milliseconds, and thought to be of → extragalactic origin. The first ever detected such burst, called the → Lorimer burst, was in 2007. It lasted only 5 milliseconds, but the single radio → pulse was dispersed over a wide range of frequencies (→ dispersion measure). This suggested a → cosmic origin for the burst, because the radiation must have passed through very distant → intergalactic clouds to be so highly dispersed. The second FRB was detected in 2012 in archival data from the Parkes Radio Telescope, the same telescope through which the original burst was seen. No temporally coincident → X-ray or → gamma ray signature was identified in association with the bursts. Most recent results suggest FRBs as a new population of explosive events at cosmological distances of up to 3 → giga  → parsecs, that is → redshifts of 0.5 to 1. While physical interpretations for this phenomenon remain speculative, they are thought to involve highly → compact objects, such as → neutron stars. See also → blitzar.

See also: The term fast radio burst was coined by Thornton et al., 2013, Science, 341, 53 (arXiv:1307.1628); → fast; → radio; → burst.

1. To attach firmly or securely in place; fix securely to something else.
   

2. To make secure, as an article of dress with buttons, clasps, etc., or a door with a lock, bolt, etc. (Dictionary.com).

Etymology (EN): From M.E. fastenen, from O.E. fæstnian; cognate with O.Fris. festnia “to make firm, bind fast,” O.Sax. fastnon, O.H.G. fastnion, O.N. fastna “to pledge, betroth.”

Etymology (PE): Darizidan, from Proto-Ir. *darz- “to attach, fasten;” cf. Av. darəz- “to attach;” Mid.Pers. handarz “advice, order, command,”
drz- “to fasten;” Mod.Pers. andarz “advice; testament,” darzan “needle,” darzi “tailor,” razé (with elimination of the initial phoneme) “a ring or staple used to fasten a door,” padarzé “a wrapper in which clothes are folded up;” cf. Skt. drah- “to fix, make firm;” Gk. drassomai “I take hold of, grasp;” Russ. deržat’ “to hold, keep” (Cheung 2007).

1. To attach firmly or securely in place; fix securely to something else.
   

2. To make secure, as an article of dress with buttons, clasps, etc., or a door with a lock, bolt, etc. (Dictionary.com).

Etymology (EN): From M.E. fastenen, from O.E. fæstnian; cognate with O.Fris. festnia “to make firm, bind fast,” O.Sax. fastnon, O.H.G. fastnion, O.N. fastna “to pledge, betroth.”

Etymology (PE): Darizidan, from Proto-Ir. *darz- “to attach, fasten;” cf. Av. darəz- “to attach;” Mid.Pers. handarz “advice, order, command,”
drz- “to fasten;” Mod.Pers. andarz “advice; testament,” darzan “needle,” darzi “tailor,” razé (with elimination of the initial phoneme) “a ring or staple used to fasten a door,” padarzé “a wrapper in which clothes are folded up;” cf. Skt. drah- “to fix, make firm;” Gk. drassomai “I take hold of, grasp;” Russ. deržat’ “to hold, keep” (Cheung 2007).

A male → parent.

Etymology (EN): M.E. fader, from O.E. fæder “father, male ancestor;” cf. O.S. fadar, Du. vader, O.N. faðir, O.H.G. fater, Ger. Vater; PIE *pəter-; cognate with Pers. pedar, as below.

Etymology (PE): Pedar, from Mid.Pers.
pidar, variant pid “father;”
O.Pers. pitā- “father;” Av. patar-; cf. Skt. pitár-; Gk. pater; L. pater (Fr. père, Sp. padre).

A male → parent.

Etymology (EN): M.E. fader, from O.E. fæder “father, male ancestor;” cf. O.S. fadar, Du. vader, O.N. faðir, O.H.G. fater, Ger. Vater; PIE *pəter-; cognate with Pers. pedar, as below.

Etymology (PE): Pedar, from Mid.Pers.
pidar, variant pid “father;”
O.Pers. pitā- “father;” Av. patar-; cf. Skt. pitár-; Gk. pater; L. pater (Fr. père, Sp. padre).

Geology: A fracture in the Earth’s crust along which the adjacent rock surfaces have been displaced relative to each other. Movement along the fault can cause → earthquakes or, in the process of mountain-building, can release underlying → magma and permit it to rise to the surface as a volcanic eruption.

Etymology (EN): M.E. faute “deficiency,” from O.Fr. faute “opening, gap; failure, flaw; lack,” from V.L. *fallita “a shortcoming, falling,” from L. falsus “deceptive, feigned, spurious,” p.p. of fallere “to deceive, be wrong.”

Etymology (PE): Gosalé, noun from gosalidan “to break; to snap asunder,” ultimately from Proto-Iranian *uisar-, from *ui- “apart” + *sar- “to break;” cf. Av. sairi- “fragment,” asarəta- “not broken;” Skt. sar- “to break, tear apart,” śūrtá- “smashed,” aśīrtá- “unharmed;” Gk. keraizo “to tear, destroy,” akeraios “unharmed;” PIE base *ker- “to hurt, harm.”

Geology: A fracture in the Earth’s crust along which the adjacent rock surfaces have been displaced relative to each other. Movement along the fault can cause → earthquakes or, in the process of mountain-building, can release underlying → magma and permit it to rise to the surface as a volcanic eruption.

Etymology (EN): M.E. faute “deficiency,” from O.Fr. faute “opening, gap; failure, flaw; lack,” from V.L. *fallita “a shortcoming, falling,” from L. falsus “deceptive, feigned, spurious,” p.p. of fallere “to deceive, be wrong.”

Etymology (PE): Gosalé, noun from gosalidan “to break; to snap asunder,” ultimately from Proto-Iranian *uisar-, from *ui- “apart” + *sar- “to break;” cf. Av. sairi- “fragment,” asarəta- “not broken;” Skt. sar- “to break, tear apart,” śūrtá- “smashed,” aśīrtá- “unharmed;” Gk. keraizo “to tear, destroy,” akeraios “unharmed;” PIE base *ker- “to hurt, harm.”

Geology: The surface of a fracture along which dislocation of adjacent rocks has taken place.

See also: → falt; → surface.

Geology: The surface of a fracture along which dislocation of adjacent rocks has taken place.

See also: → falt; → surface.

The geological process leading to the formation of → faults.

See also: Verbal noun, → fault.

The geological process leading to the formation of → faults.

See also: Verbal noun, → fault.