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

The amount of → thermal energy that is absorbed or released by a unit amount of a substance in the process of a phase change under conditions of constant pressure and temperature.

→ latent; → heat.

Of or relating to the → side; situated at, proceeding from, or directed to a side (Dictionary.com).

M.E., from O.Fr. latéral and directly from L. lateralis "belonging to the side," from latus "the side, flank; lateral surface."

Kenâri, relating to kenâr, → side.

General: To regulate by or adjust to a certain measure or proportion; tone down. Physics: To alter the value of some parameter characterizing a periodic oscillation. → modulation.

From L. modulatus pr.p. of modulari "to regulate, measure off properly," from modulus "small measure," diminutive of modus "measure, manner," → mode.

Degarâhangidan, from degar "other, another," denoting change, variant digar (Mid.Pers. dit, ditikar "the other, the second;" O.Pers. duvitiya- "second," Av. daibitya-, bitya- "second;" Skt. dvitiya- "second," PIE *duitiio- "second") + âhang "melody, pitch, tune, modulation" (ultimately from Proto-Iranian *āhang-, from prefix ā- + *hang-, from PIE base *seng^wh- "to sing, make an incantation;" cf. O.H.G. singan; Ger. singen; Goth. siggwan; Swed. sjunga; O.E. singan "to chant, sing, tell in song;" maybe cognate with Gk. omphe "voice; oracle") + -idan infinitive suffix.

A combination of two or more waves resulting in the production of frequencies not present in the original waves, the new frequencies being usually the sums and differences of integral multiples of the frequencies in the original waves.
A wave which varies in some characteristic in accordance with the variations of a modulating signal. Compare continuous wave. See modulation

Modulated, p.p. of → modulate; → wave.

Adjective meaning flattened, as → oblate spheroid. Opposed to → prolate.

From L. ob- "toward" + latus, abstracted from its opposite, prolatus "lengthened."

Pax "oblate," of unknown etymology.

An ellipsoid produced by rotating an ellipse through 360° about its minor axis. Compare with → prolate spheroid.

→ oblate; → spheroid.

The property possessed by a round body that is flattened at the poles.

Noun from → oblate.

(polar flattening) The ratio of the difference between equatorial and polar diameters to the equatorial diameter. A sphere has an oblateness of 0; an infinitely thin disk has an oblateness of 1 (Ellis et al., 2007, Planetary Ring Systems, Springer).

→ optical; → oblateness.

To have, produce, or generate oscillations. → vibrate.

From L. oscillatus, p.p. of oscillare "to swing," from oscill(um) "swing" + -ate a suffix forming verbs from L. words.

Navidan "to swing, oscillate," from nâvidan, literally "to swing like a ship," from nâv "ship;" O.Pers./Av. *nāv-, O.Pers. nāviyā- "fleet;" Skt. nau-, nava- "ship, boat;" Gk. naus "ship;" PIE *nau- "boat."

Geometry: Of a curve, to touch another curve so as to have the same tangent and curvature at the point of contact.

From L. osculatum p.p. of osculari "to kiss," from osculum "kiss," literally "little mouth," diminutive of os "mouth;" PIE *os-/*ous- "mouth;" cf. Av. āh- "mouth;" Skt. ās-, āsán- "mouth;" Hittite aiš- "mouth;" O.Ir. á "mouth;" O.N. oss "mouth."

Âbusidan, from â- a nuance prefix + busidan "to kiss," related to buyidan "to smell," buy "smell, scent;" Mid.Pers. bôy, bôd "smell, scent; consciousness," bôyidan "to smell," Mod./Mid.Pers. bustân "garden," Parthian (prefixed *pati-) pdbws- "to desire; to hope for;" Av. baod- "to perceive, notice, become aware of; to smell of," baoδi- "smell, fragrance," baozdri- "who gets to know sexually;" cf. Skt. bodh- "to wake, awaken; to perceive, pay attention," Buddha "awakened, enlightened;" Gk. peuthomai "to learn, hear;" Lith. budeti "to wake;" O.C.S. bljusti "to take care;" PIE base *bheudh- "to be aware, to make aware."

The roof of the → mouth, separating the oral and nasal cavities. → hard palate; → soft palate.

M.E., from O.Fr. palat and directly from L. palatum "roof of the mouth."

Kâm "roof of the mouth," of unknown origin.

1) Of or relating to minute separate → particles.
2) A particulate → substance.

From Mod. L. particulatus, from particula, → particle.

From pârul, → particle, + suffix -é or -mand.

Meteorology: A complex → mixture of → microscopic → particles and → liquid droplets suspended in the → atmosphere, especially pollutants.

→ particulate; → matter.

The postulate that the energy of oscillators in a blackbody is quantized by E = nhν, where n = 1, 2, 3, ..., h is Planck's constant, and ν the frequency.

→ Planck; → postulate.

A piece of glass with plane parallel surfaces used to admit light into an optical system and to exclude dirt and moisture.

→ plane; → parallel; → plate.

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.