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

A substance which remains → deformed after an applied → force ceases to act.

→ plastic; → substance.

The property which enables a material to be → deformed permanently without → rupture during the application of a → force. An → elastic material becomes plastic above its → yield point. See also → elasticity, → ductility.

→ plastic; → -ity.

1) Optics: Any crystalline material whose length is much less than its measured diameter. → half-wave plate.
2) A flat piece of material on which a picture or text has been produced.
3) Any of the large movable segments into which the Earth's lithosphere is divided. → plate tectonics.

M.E., from O.Fr. plate "thin piece of metal," from M.L. plata "plate, piece of metal," perhaps via V.L. *plattus, from Gk. platys " flat, broad."

1) Tiqé, from tiq "blade," related to tiz "sharp," variants tig, tež, tej, tij; Mid.Pers. tigr, têz, têž "sharp," O.Pers. tigra- "pointed," tigra.xauda- "pointed helmet (epithet of Scythians)," Av. tiγra- "pointed," tiγray- "arrow," tiži.arštay- "with the pointed spear," cf. Skt. tikta- "sharp, pungent, bitter," tejas- "sharpness, edge, point or top of a flame;" PIE base *st(e)ig- "to stick; pointed." Cognates in other IE languages: Gk. stizein "to prick, puncture," stigma "mark made by a pointed instrument," L. in-stigare "to goad," O.H.G. stehhan, Ger. stechen "to stab, prick," Du. stecken, O.E. sticca "rod, twig, spoon," E. stick.
2); 3) loanword from Fr., as above.

The celestial coordinates of the center of the field of an astronomical photographic plate.

→ plate; → center.

The scale factor for converting linear measure on a photographic plate to angular measurement on the sky.

→ plate; → scale.

The theory supported by a wide range of evidence in which the Earth's crust is composed of several large, thin, relatively rigid plates that move relative to one another. The interaction of the plates at their boundaries causes seismic and tectonic activity along these boundaries. See also → continental drift.

→ plate; → tectonics.

1) An extensive area with a fairly level surface raised sharply above adjacent land.
2) A period, phase, or state of little or no growth or decline in something. → Spite plateau.

From Fr. plateau, from O.Fr. platel "flat piece of metal, wood, etc.," diminutive of plat "flat surface or thing," → plate.

Taxtâl, from taxt "flat;" Mid.Pers. taxtag "tablet, plank, (chess)board" + -âl, → -al.

1) A small platelike body.
2) One of a variety of forms taken on by → snowflakes.
3) A tiny cell occurring in the blood of vertebrates and involved in clotting of the blood. Formerly called thrombocyte.

→ plate; → -let.

A silvery metallic → chemical element which is tenacious, malleable, and ductile; symbol Pt. → Atomic number 78; → atomic weight 195.08; → melting point 1,772°C; → boiling point 3,827±100°C; → specific gravity 21.45 at 20°C; → valence +2 or +4. It has several short-lived → radioactive isotopes, with the exception of ¹⁹⁰Pt whose → half-life is 6.0 x 10¹¹ years.

From Sp. platina diminutive of plata "silver," from O.Fr. → plate "sheet of metal." The first known reference to platinum can be found in the writing of Italian physician, scholar, and poet Julius Caesar Scaliger (1484-1558). He reported seeing the metal during a visit to Central America in 1557. Aborigines knew of no use for the metal and regarded it as a nuisance in their search for gold and silver. By the end of the 17th century, the Spanish conquistadors started developing the river soil looking for gold and found some gray looking beads together with the gold. They called those little silver beads platina "small silver." They became known as platina del Pinto "granules of silvery material from the Pinto River," a tributary of the San Juan River in the Chocó region of Colombia. The first complete description of platinum was given in 1735 by the the Spanish explorer and naval officer Antonio de Ulloa (1716-1795).

Pelâtin, loanword from Fr.

One of the six metals → platinum (Pt), → iridium (Ir), → osmium (Os), → palladium (Pd), → rhenium (Rh), and → ruthenium (Ru) that are grouped together in the → periodic table. They are relatively hard and resistant to corrosion and are used in jewellery and in some industrial applications. All are resistant to chemical attack.

→ platinum; → group; → element.

The time required for a complete revolution of the Earth's pole on the celestial sphere as the result of → precession. A Platonic year is equal to 25 800 years.

Of or pertaining to Gk. philosopher Plato, from Gk. Platon "broad-shouldered," from platys "broad." → year.

A frequency distribution with negative → kurtosis, which has a smaller "peak" around the mean than the corresponding normal distribution. → leptokurtic.

From Gk. platys "flat", → plate + → kurtosis.

Past-afrâšté, literally "lowly elevated," from past "low; plain" (Mid.Pers. past; proto-Iranian *pasta- "fallen," from *pat- "to fall," cf. Av. pat- "to fall; to fly; to rush," patarəta- "winged;" Mid.Pers. opastan "to fall," patet "falls;" Mod.Pers. oftâdan "to fall," oft "fall;" 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") + afrâšté "raised, elevated, erect," p.p. of afrâštan, → kurtosis.

Pleasing, agreeable, or enjoyable; giving pleasure.

M.E., from O.Fr. plaisant, from plaisir, → pleasure.

1) To act to the pleasure or satisfaction of.
2) To be the pleasure or will of (Dictionary.com).

From M.E. plesen, plaisen, from O.Fr. plaisir "to please, give pleasure to, satisfy," from L. placere "to be acceptable, be liked, be approved," related to placare "to soothe, quiet."

Âzušidan, from prefix â- + zušé, → pleasure, + infinitive suffix -idan.

1) The state or feeling of being pleased.
2) Enjoyment or satisfaction derived from what is to one's liking; gratification; delight.
3) Worldly or frivolous enjoyment (Dictionary.com).

M.E., from O.Fr. plesir, plaisir "enjoyment, delight, desire," from plaisir "to please," from L. placere "to please, give pleasure."

Zusé, from Av. zuš- "to take pleasure;" related to O.Pers. daušta- "friend," Mid.Pers. dôš- "to love, like, choose," dôšišn "pleasure, liking;" Parthian zwš "love;" Mod.Pers. dôst, dust "friend;" cf. Skt. jos- "to like, enjoy;" Gk. geuomai "to taste;" L. gusto "I taste;" gustus "taste, enjoyment."

A prominent → open cluster in the constellation → Taurus, popularly called the Seven Sisters. It is a very young cluster of several hundred stars (with spectral types B6 and later), spanning over 1.5 degrees on the sky and about 400 → light-years distant. Six members of the cluster are visible to the → naked eye, the brightest one being → Alcyone. The cluster contains extensive nebulosity, consisting of dust clouds that reflect the light of the → embedded stars. Other designations: M45, NGC 1432.

In Gk. mythology, the seven daughters of Atlas and Pleione, transformed by Zeus into seven stars, from L., from Gk. Pleiades, perhaps literally "constellation of the doves," from a shortened form of peleiades, plural of peleias "dove," from PIE base *pel- "dark-colored, gray."

Parvin, variants Parv, Parvé, Paran, Parand, Parviz, Kurd. Pêrû, Pashtu Pêrûne, Baluchi Panvar; Mid.Pers. Parwiz. According to Bartholomae, it originates from Av. Paoiryaēini-, the first component paoirya- denoting "first." Alternatively, the first element in Parvin may be related to Av. parav-, pauru-, pouru- "full, much, many" (Mod.Pers. por "full, much, very;" Mid.Pers. purr "full;" O.Pers. paru- "much, many," from par- "to fill;" PIE base *pelu- "full," from *pel- "to be full;" cf. Skt. puru- "much, abundant;" Gk. polus "many," plethos "great number, multitude;" O.E. full), denoting "many, numerous," because the object contains several stars.

A star in the constellation → Taurus and a member of the → Pleiades star cluster. Pleione is a blue-white B-type → main sequence → dwarf with a mean apparent magnitude of +5.09. It is a variable star and its brightness varies from magnitude +4.77 to +5.50. It is approximately 380 light-years from Earth.

Pleione was an Oceanid nymph. She lived in a southern region of Greece called Arcadia, on a mountain named Mount Kyllini. She married Atlas and gave birth to the Hyades, Hyas and the Pleiades.

The earliest Epoch of the Quaternary Period, beginning about 1.6 million years ago and ending 10,000 years ago. Commonly known as the "Ice Age," a time with episodes of widespread continental glaciation.

From Gk. pleisto(s), superlative of Polys "much," cognate with Pers. por, → full, + -cene from Gk. kainos "new, recent."

The property of certain crystals of exhibiting different colors when viewed from different directions under transmitted light. This is because the degree with which certain birefringent crystals transmit polarized light is different, depending on whether the ray is ordinary or extraordinary. Pleochroism is the general term for both dichroism, which is found in uniaxial crystals (crystals with a single optic axis), and trichroism, found in biaxial crystals (two optic axes).

From pleochro(ic), from pleo- prefix meaning "more," from Gk. pleion "more," cognate with Pers. por, → full, + chroic, from chroos "skin, color" + -ism.

Candfâmi, from cand "so many, much; how many, how much" (O.Pers. yāvā "as long as;" Av. yauuant- [adj.] "how great?, how much?, how many?," yauuat [adv.] "as much as, as far as;" cf. Skt. yāvant- "how big, how much;" Gk. heos "as long as, until") + fâm "color," + -i noun suffix.

A → supernova remnant which has a filled center rather than being a shell. The internal region is "filled" by energetic particles streaming from a rotating → pulsar. The → Crab Nebula is the archetypal plerion.

Plerion, from Gk. pleres "full," akin to Pers. por "full," → poly-.