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

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.

1) A state of society in which various religious, ethnic, racial, and political groups are allowed to thrive in a single society.
2) Philo.: A belief that there are more than two kinds of principles, as contrasted to the → dualism and → monism.

→ plural; → -ism.

The state or fact of being plural or numerous.

→ plural + → -ity.

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."

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.

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.

A → radioactive → chemical element, symbol Pu. → Atomic number 94; → mass number of most stable isotope 244; → melting point 640 °C; → boiling point 3,235 °C. It was first synthesized in 1940 by American chemists Glenn T. Seaborg, Edwin M. McMillan, Joseph W. Kennedy and Arthur C. Wahl in the → nuclear reaction: ₉₂U²³⁸ + ₀n¹→ ₉₃Np²³⁹ + β^- (23.5 minutes) → ₉₄Pu²³⁹ + β^- (2.36 days). The → half-life of ₉₄Pu²³⁹ is 2.44 × 10⁴ yr. Plutonium-239 is a → fissile isotope.

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.

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

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.

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

→ poach; → -er.

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

→ poach; → -ing.

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.

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.

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.

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.

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.

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) Âmâjidan, 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."

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

→ point; → mass.

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

→ point; → source.

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").