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

1) Any of various herbaceous plants having parts that are used as food, such as peas, beans, cabbage, potatoes, cauliflower, and onions.
2) Botany: Of, relating to, characteristic of, derived from, or consisting of plants or plant material (e.g. vegetable oils) (TheFreeDictionary.com).

→ vegetate; → -able.

1) Sabzijât "class or category of greens," from sabzi, → green, + -jât a suffix denoting class, group, or division of things.
2) Giyâhi, related to giyâh, → plant.

Of, relating to, or characteristic of plants.

→ vegetate; → -al.

1) To grow or sprout as a plant by nutriment imbibed through roots and leaves.
2) To lead a passive life without much physical, mental, or social activity.

Ultimately from L. vegetatus, p.p. of vegetare "to enliven, to animate," from vegetus "vigorous, enlivened, active," from vegere "to be alive, active;" akin to Skt. vaja- "force, strength;" PIE root *weg- "to be strong, be lively."

Giyâhidan, infinitive forum giyâh, → plant.

1) All the plants or plant life of a place.
2) (Botany) Plant life as a whole, especially the plant life of a particular region.
3) The act or process of vegetating.

Verbal noun from → vegetate.

1) Of, relating to, or characteristic of plants or their growth.
2) Noting the parts of a plant not specialized for reproduction (TheFreeDictionary.com).

→ vegetate; → -ive.

Giyâhvâr, from giyâh, → plant, + -vâr suffix denoting "resembling, like," → -oid.

1) A piece of opaque or transparent cloth worn by women as a covering for the head and shoulders.
2) Something that covers, screens, or conceals.

M.E. veile; O.Fr. voile "a head-covering" (also "sail"), from L. vela, plural of velum "curtain, covering; sail."

Vâšâmé "veil," variants vâšâm, bâšâmé, bâšâm, from Mid.Pers. *varšâmak (loaned in Arm. varšamak "veil, scarf"); cf. Sogd. wâršâmé "veil;" from Proto-Ir. *varšāmaka-, from *varšām-, from *varš-, from var- "to cover;" cf. Av. var- "to cover, conceal;" Skt. var- "to cover;" Mid.Pers. warr "garment," prefixed uzvâr-, uzvârdan "to uncover, show, apprehend, interprete;" Mod.Pers. šalvâr "trousers" (literally "thigh cover;" the first component šal "thigh," šelang "thigh; step, distance between feet when walking," cognate with Gk. skelos "leg"); Kurd. (Soriani) barg "cover; clothes," da barg girtin "to wrap in a cover."

A part of the → Cygnus loop, an old → supernova remnant.

→ veil; → nebula.

1) General: An act of covering with or as if with a veil.
2) A weakening of the → spectral lines of a star that occurs when the spectral lines are filled in by → continuum emission or light from a → companion star.

Verbal noun from veil (v.).

Any of the tubes forming part of the blood circulation system of the body, carrying mainly oxygen-depleted blood towards the heart (OxfordDictionaries.com).

M.E. veine, from O.Fr. veine "vein, artery, pulse," from L. vena "a blood vessel," also "a water course, a vein of metal," of unknown origin.

Siyâhrag, literally "black vessel," from siyâh, → black, + rag, → vessel.

The Sail. A part of the constellation Argo in the Southern hemisphere, which was later divided into three parts, the others being Carina and Puppis. Vela is situated at about 10h right ascension, -50° declination. Abbreviation: Vel; Genitive: Velorum.

From L. vela, plural of velum "sail, curtain, covering," velare "to cover, veil."

Bâdbân "sail," literally "wind keeper," from bâd→ wind + -bân a suffix denoting "keeper, guard," sometimes forming agent nouns or indicating relation, → host.

A pulsar with a short period (89 milliseconds) associated with the → Vela supernova remnant. It is approximately 1500 light-years distant. The Vela pulsar is one of the few pulsars detectable optically. Its optical flashes, of visual magnitude 26, were detected in 1977. Also named PSR 0833-45.

→ Vela; → pulsar.

A → supernova remnant located in the southern Milky Way in the constellation → Vela. It has a large angular diameter of about 8° and lies 250 ± 30 pc away (Cha et al. 1999, ApJ 515, L25). Its overall emission is dominated by the interaction of the → supernova blast wave with the → interstellar medium. This SNR is also notable for a number of protrusions extending well beyond its rim, which were suggested to be fragments of ejecta from the supernova explosion. X-ray spectroscopy has since confirmed several of these protrusions to indeed be strongly enriched with ejecta. The age of the SNR is estimated to be ~11,000 years, based on the spin-down rate of the associated → Vela pulsar, but ages as large as 20,000-30,000 years have also been argued.

→ Vela; → supernova remnant.

A compact radio source about 1500 light-years distant associated with the Vela supernova remnant. It has a nonthermal radio spectrum and is about 20 percent polarized. It is associated with the Gum Nebula, the Vela pulsar, and the X-ray source 2U 0832-45.

→ Vela; X for → X ray.

The time rate of change of position in a given direction, measured as length per unit time. → speed.

L. velocitatem (nominative velocitas) "swiftness, speed," from velox (genitive velocis) "swift."

Tondâ, from tond "swift, rapid, brisk; fierce, severe" (Mid.Pers. tund "sharp, violent;" Sogdian tund "violent;" cf. Skt. tod- "to thrust, give a push," tudáti "he thrusts;" L. tundere "to thrust, to hit" (Fr. percer, E. pierce, ultimately from L. pertusus, from p.p. of pertundere "to thrust or bore through;" PIE base *(s)teud- "to thrust, to beat") + noun suffix -â.

A plot of the radial velocity of an object against time, derived from the Doppler shift of spectral lines.

→ velocity; → curve.

The → standard deviation of a velocity → distribution. It indicates how objects of the sample move relative to one another. Objects with similar velocities have a small velocity dispersion, whereas objects with very different velocities have a large velocity dispersion.

→ velocity; → dispersion.

Fluid Mechanics: The rate at which the velocity changes with the distance across the flow. When a fluid flows past a stationary wall, the fluid right close to the wall does not move. However, away from the wall the flow speed is not zero. Therefore a velocity gradient exists, which is due to adhesive, cohesive, and frictional forces. The amount of the velocity gradient is characteristic of the fluid.

→ velocity; → gradient.

In the theory of → radiation-driven winds, an equation that describes the behavior of the → wind velocity of → hot stars as a function of distance from the star. This velocity β-law is given by the expression: v(r) = v_∞(1 - R_*/r)^β, where v_∞ is the → terminal velocity, R_* is the stellar radius, and r the distance from the center. For → O-type stars, the exponent is estimated to be β = 0.8.

→ velocity; → law.

A → physical constant which represents the ultimate speed limit for anything moving through space, according to the theory of → special relativity. It is the speed of propagation of → electromagnetic waves in a vacuum, equal to 299,792.458 km/s (nearly 3 x 10⁸ m/s). The velocity of light appears as the connecting link between mass and energy in the → mass-energy relation. Usually denoted by c, from L. celeritas "swiftness," from celer "swift," → acceleration.

→ velocity; → speed; → light.

→ dynamic pressure.

→ velocity; → pressure.