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

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.

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.

→ falsifiable; → -ity.

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

→ falsify; → -able.

1) To show or prove that a theory is incorrect or false.
2) To alter something in order to deceive.

Verb from → false.

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

→ false; → -ity.

A group of entities with similar properties and common origin. → family of curves, → family of distributions, → family of sets, → comet family.

From L. familia "household, the slaves of a household," from famulus "servant," of unknown origin.

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.

→ family; → curve.

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

→ family; → distribution.

A → collection of → subsets of a set.

→ 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).

M.E., from O.E. fann, from L. vannus "a basket or shovel for winnowing grain," related to ventus, → wind.

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.

→ Fanaroff-Riley classification; → class.