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

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.

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."

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.

→ 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.

→ factor + -ial, from L. -alis, → -al.

The operation of resolving a quantity into factors.

→ 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.

Facula, from L. fac-, fax "torch" + -ula, → -ule.

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.

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.

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."

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^heHu- "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.

Verbal noun from → fail.

1) Lacking brightness, vividness, clearness, loudness, strength; feeble; exhausted.
2) To lose consciousness temporarily; to lose brightness (Dictionary.com).

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."

Tâm, from Pers. tâm "feeble, fragile, weak," ultimately from Proto-Ir. *tamH- "to faint, be tired;" cf. Khotanese ttāmā "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.

→ 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.

→ 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).

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."

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.

Of unknown origin.

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.

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").

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.

From L. fallacia "deception," from fallere "to deceive, trick, cheat; fail, be defective."

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.

From O.Fr. fals, faus, from L. falsus "deceived, erroneous, mistaken," p.p. of fallere "to deceive, disappoint."

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.

→ 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.

→ 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.

→ 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.

→ false; → vacuum.