An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 1001

Fr.: pluriel   

1) Consisting of, containing, or pertaining to more than one thing.
2) Grammar: A form of nouns, pronouns, and verbs that refers to more than one thing or (in languages that recognize the dual form) more than two.

M.E., from O.Fr. plurel "more than one," from L. pluralis "of or belonging to more than one," from plus (genitive pluris) "more," → plus.

Bišâl, from biš "much, more; great," → plus, + -âl, → -al.


Fr.: pluralité   

The state or fact of being plural or numerous.

plural + → -ity.


Fr.: plus   

1) (prep.) With the addition of.
2) (adj.) Additional; → positive.
3) (n.) An addition; a positive quantity; the → plus sign.

L. plus "more," cognate with Gk. polys "much," Pers. por, → full.

Bišan, from biš "much, more; great" + suffix -an, → minus. The first component from Mid.Pers. veš "more, longer; more frequently," related to vas "many, much" (Mod.Pers. bas); O.Pers. vasiy "at will, greatly, utterly;" Av. varəmi "I wish," vasô, vasə "at one's pleasure or will," from vas- "to will, desire, wish."

plus sign
  نشان ِ بیشن   
nešân-e bišan

Fr.: sign plus   

The symbol + indicating summation or a positive quantity. The sign is believed to be a shortened form of the L. word et denoting "and" which was the term for addition. The signs + and - first appeared in an arithmetic book by Johannes Widmann entitled Behennde und hübsche Rechnung, published in Leipzig in 1489.

plus; → sign.

Pluton (#)

Fr.: Pluton   

A → dwarf planet in the → solar system which until 2006 was known as the 9th major planet. Pluto revolves around the → Sun in a highly elliptical orbit at a mean distance of 39.5 → astronomical units once every about 248 years. The orbit → eccentricity is 0.25 (compare with the Earth's 0.02) yielding a → perihelion distance of 29.66 → astronomical units and an → aphelion distance of 48.87 AU. Its → orbital inclination is 17 degrees, which is much higher than those of the other planets. Pluto's mass is 1.308 × 1022 kg, that is 0.00218 Earth mass (0.177 Moon mass), its equatorial radius ib 0.19 Earth radius, and its → rotation period is equal to 6.39 Earth days. It has five known → satellites, in order of distance from Pluto: → Charon, → Styx, → Nix, → Kerberos, and → Hydra. Pluto's radius is estimated to be about 1150 km (0.18 Earths). Pluto is smaller than seven of the solar system's satellites (the → Moon, → Io (Jupiter I) , → Europa, → Ganymede, → Callisto, → Titan, and → Triton). Pluto's surface has an estimated temperature of 37.5 K and is composed of more than 98% → nitrogen  → ice, with traces of → methane and → carbon monoxide.

In Roman mythology, Pluto is the god of the underworld and Judge of the dead, from L. Pluto, Pluton, from Gk. Plouton "god of wealth," literally "wealth, riches." Pluto was the son of Saturn. The alternative Gk. name is Hades.


Fr.: plutonium   

A radioactive chemical element, symbol Pu. Atomic number 94; mass number of most stable isotope 244; melting point 641°C; boiling point 3,232°C.

The name derives from the planet → Pluto. It was selected because it is the next planet in the solar system beyond the planet → Neptune and the element plutonium is the next element in the → periodic table beyond → neptunium.


Fr.: braconner   

To trespass, especially on another's game preserve, in order to steal animals or to → hunt; to take game or fish illegally (

M.E., from M.Fr. pocher "to thrust, poke," from O.Fr. pochier "poke out, gouge, prod," related to poke (v.), from a Germanic source (compare M.H.G. puchen "to pound, beat, knock," Ger. pochen, Middle Dutch boken "to beat") related to poke (v.).

Beškaridan, from beškar(d), bišgar(d) "hunter, fowler; chase; game; place for hunting," variant of šekâr, → hunt.


Fr.: braconnier   

A person who trespasses on private property, especially to catch fish or game illegally ( See also → hunter.

poach; → -er.


Fr.: braconnage   

The illegal taking of wildlife, in violation of local, state, federal or international law.

poach; → -ing.

Pogson's ratio
  وابر ِ پوگسون   
vâbar-e Pogson

Fr.: rapport de Pogson   

The constant 2.512, which is the 5th → root of 100 (2.5125 = 100); the ratio between two successive stellar → magnitudes.

Pogson's relation; → ratio.

Pogson's relation
  بازانش ِ پوگسون   
bâzâneš-e Pogson

Fr.: relation de Pogson   

The equation that expresses the → magnitude  → difference between two objects in terms of the → logarithm of the → flux  → ratio:
I1/I2 = 2.5(m2 - m1), or
m2 - m1 = 2.5 log(I1/I2),
where m is → apparent magnitude, I flux, and log the logarithm to base 10.

Named after Norman Robert Pogson (1829-1891), the English astronomer, who introduced the magnitude scale in 1856; → relation.

Poincaré recurrence theorem
  فربین ِ باز‌آمد ِ پو‌آنکاره   
farbin-e bâzâmad-e Poincaré

Fr.: théorème de récurrence de Poincaré   

In an → isolated system, any initial state will occur again in the course of the → evolution of the system over a sufficiently long but finite → time.

Poincaré sphere; → recurrence; → theorem.

Poincaré sphere
  کره‌ی ِ پو‌آنکاره   
kore-ye Poincaré

Fr.: sphère de Poincaré   

A representation that permits an easy visualisation of all different states of → polarization of a vector wave. The equator represents → linear polarization; the north pole corresponds to right-circular and the south pole to left- → circular polarization.

Named after Henri Poincaré (1854-1912), French mathematician and theoretical physicist, and a philosopher of science; → sphere.

Poinsot's motion
  جنبش ِ پویءنسو   
jonbeš-e Poinsot

Fr.: mouvement à la Poinsot   

The motion of a torque free rotating rigid body in space, in general whose angular velocity vector precesses regularly about the constant angular momentum factor.

After Louis Poinsot (1777-1859), French physicist and mathematician. He was the inventor of geometrical mechanics, showing how a system of forces acting on a rigid body could be resolved into a single force and a couple.

  ۱) نقطه، پنده؛ ۲) آماجیدن   
1) noqté (#), pandé (#); 2) âmâjidan

Fr.: 1) point; 2) pointer   

1a) General: A sharp or tapering end, as of a dagger; a projecting part of anything.
1b) Physics: Position or time of occurrence, as in boiling point, freezing point, etc.
1c) Math.: A dimensionless geometric element whose location in space is defined solely by its coordinates.
2) To direct a telescope toward a particular position on the sky.

M.E. point(e); O.Fr. point "dot, mark, place, moment;" L. punctum noun use of neuter p.p. of pungere "to prick, pierce."

1) Noqté, loan from Ar. Pandé, variants in classical dictionaries pindé, pendé, fand "a point, dot, mole, freckle;" cf. Skt. prānta- "point, tip, border," from pra "before, forward," → pro-, + ánta- "end, limit, term;" Pali, panta- "remote, solitary;" Prakrit panta " last;" Sindhi pandu "border of a garment;" Lahnda pand, pad "end, top of sugar cane."
2) &ACIRC;mâjidan verb from âmâj "aim, goal," from Proto-Iranian base *āma-, from prefix *ā- + *ma- "to measure;" cf. Av. mati- "point, tip;" O.Pers./Av. mā(y)- "to measure;" Pers. mun/mân "measure," as in Pers. terms pirâmun "perimeter," âzmun "test, trial," peymân "measuring, agreement," peymâné "a measure; a cup, bowl;" cf. Skt. mati "measures," matra- "measure," Gk. metron "measure," L. metrum; PIE base *me- "to measure."

point mass
  نقطه‌جرم، پنده‌جرم، جرم ِ نقطه‌وار، ~ پنده‌وار   
noqté jerm, pandé jerm, jerm-e noqtevâr, ~ pandevâr

Fr.: masse ponctuelle   

A hypothetical object which can be thought of as infinitely small.

point; → mass.

point source
  نقطه‌خن، پنده‌خن، خن ِ نقطه‌وار، ~ پنده‌وار   
noqté xan, pandé xan, xan-e noqtevâr, pande-ye ~

Fr.: source ponctuelle   

A source of radiation at a great distance from the observer; an ideal source of infinitesimal size.

point; → source.

point spread function (PSF)
  کریای ِ گسترش ِ نقطه، ~ ~ پنده   
karyâ-ye gostareš-e noqté, ~ ~ pandé

Fr.: fonction d'étalement du point   

The two-dimensional intensity distribution about the image of a point source.

point; → spread; → function.



The two stars that form the front of the Big Dipper's bowl, away from the handle. More specifically, the stars Dubhe (α Ursae Majoris) and Merak (β Ursae Majoris). A line through β to α passes close to the North Star and they are used for finding it.

point + -er.

Dorahnemâ, literally "the two guides," from do "two" + rah, râh "way, path" (from Mid.Pers. râh, râs "way, street," also rah, ras "chariot;" from Proto-Iranian *rāθa-; cf. Av. raθa- "chariot;" Skt. rátha- "car, chariot," rathyā- "road;" L. rota "wheel," rotare "to revolve, roll;" Lith. ratas "wheel;" O.H.G. rad; Ger. Rad; Du. rad; O.Ir. roth; PIE *roto- "to run, to turn, to roll") + nemâ agent noun of nemudan "to show" (Mid.Pers. nimūdan, nimây- "to show," from O.Pers./Av. ni- "down; into" (Skt. ni "down," nitaram "downward," Gk. neiothen "from below," cf. E. nether, O.E. niþera, neoþera "down, downward, below, beneath," from P.Gmc. *nitheraz, Du. neder, Ger. nieder; PIE *ni- "down, below") + māy- "to measure;" cf. Skt. mati "measures," matra- "measure;" Gk. metron "measure;" L. metrum; PIE base *me- "to measure").


Fr.: pointage   

The act or process of directing a telescope. → point.
The direction in the sky to which the telescope is pointed. Pointing also describes how accurately a telescope can be pointed toward a particular direction in the sky.

Verbal noun of → point.

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