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

A component of the → interstellar medium consisting of an extremely tenuous (density 0.1 to 10 cm^-3) and relatively warm gas (temperature about 8,000 K) filling the space between denser neutral and ionized gas. Hydrogen is partly ionized, partly atomic and observed by the → 21-centimeter line in emission.

→ warm; → intercloud medium.

The space containing a cluster of galaxies filled with a tenuous gas of temperature 10⁵ to 10⁷ K and density 10^-6 to 10^-4 cm^-3. WHIM has been continuously shock-heated during the process of structure formation. It is so highly ionized that it can only absorb or emit far-ultraviolet and soft X-ray photons, primarily at spectral lines of highly ionized C, O, Ne, and Fe. WHIM is thought to be the main reservoir of missing baryons.

→ warm; → hot; → intergalactic medium.

The process of becoming warmer; a rising temperature. → backwarming, → heating.

→ warm; → -ing.

The vertical twisting of a → galactic disk in its outer parts. Many → spiral galaxies, including our Milky Way, appear to have warps in the outer reaches of their stellar and gas disks. The rotating body of stars and gas that characterizes a spiral galaxy is generally flat, but the outer regions may deviate from the plane of the disk. The causes are multiple, some warps can come from spontaneous instability, some result from interactions between galaxies, and many reflect the external gas → accretion from intergalactic matter filaments.

M.E. werpen, OE weorpan "to throw;" cf. O.S. werpan, O.N. verpa "to throw," Swed. värpa "to lay eggs," Du. werpen, Ger. werfen "to throw; to distort." Related to warp "threads running lengthwise in a fabric."

Tâb "twisting, bending, waving, a curling lock," variants tâv, tow, tew, from tâbidan, tâftan "to twist, to spin, to bend, to crook," p.p. tâftah "spun, silk or linen cloth," loaned into E. as taffeta (from O.Fr. taffetas, from It. taffeta); similarly Gk. tapetion "little carpet" is probably from this Iranian origin (from which tapestry, tapis); Proto-Ir. *tâp- "to twist, to wind;" cf. L. tempus "time (span);" Lith. tempti "to stretch;" Russ. tepsti "to tighten."

A → galactic disk that exhibits a → warp phenomenon.

→ warp; → disk.

1) Geology: The slight flexing or bending of the Earth's → crust on a broad or regional scale, either upward or downward.
2) Of a galaxy, → warped disk, → warp.

Verbal noun from → warp (v.).

A hard rough lump growing on the skin, caused by infection with certain viruses and occurring typically on the hands or feet (TheFreeDictionary.com).

M.E., from O.E. weart "wart," cf. O.Norse varta, O.Frisian warte, Du. wrat, O.H.G. warza, Ger. Warze, Swed. varta, Russ. vered "ulcer," perhaps ultimately from the same source as L. verruca "a steep place, swelling, wart" (Fr. verrue, Sp. verruga, Catalan berruga, It. verruca), ultimately from PIE *uer-s- "a steep place, height," from *uer- "highland, high place, top;" cf. Gk. ouranos "sky."

Zegil "wart," maybe related to Pers. gereh "knot," ultimately from prefixed (*uz-, → ex-) *graθH- "to tie (a knot)."
Veruk "wart," variants vâruk, vâru, veri, var, oru, bâlu, bâlik, belik (also "the clitoris" in dialects), belije, bâlur, bali, maybe variants of zegil "wart," as above, ultimately from Proto-Ir. *graθH- "to tie (a knot)."

To apply → water or other → liquid in order to cleanse.

M.E. washen; O.E. wascan, wæscan; cf. O.N. vaska, M.Du. wasscen, Du. wassen, Ger. waschen, from stem *wat-, the root of → water.

Mid.Pers. šustan, šuy- "to wash;" Av. xšaoδah- "flush of water," xšudra- "liquid, fluid; semen;" cf. Skt. ksod- "to dissolve;" Proto-Ir. *xšaud- "to wash" (Cheung 2007).

A stellar catalog which is the world's principal database of astrometric → double star information. It is maintained by the United States Naval Observatory. The WDS Catalog contains positions (J2000), discoverer designations, epochs, position angles, separations, magnitudes, spectral types, proper motions, and, when available, Durchmusterung numbers and notes for the components of 142552 systems (as of Feb 27 2018).

Washington, referring to the location of the United States Naval Observatory in Northwest Washington, D.C; → double; → star; → catalog.

Unwanted or unusable items, remains, or byproducts. → nuclear waste; → radioactive waste.

M.E., from O.Fr. wast, g(u)ast, from L. vastum, neuter of vastus "waste."

Âxâl "waste, rubbish," of unknown origin.

The normal oxide of hydrogen with formula H₂O. Pure water's → melting point is 0°C and its → boiling point 100 °C at sea level. Water has a → maximum density at very nearly 4°C of (by definition) 1.0000 g cm^-3. It then expands as its temperature drops to 0°C, the density being 0.9998 g cm^-3 . On freezing, it expands still further, giving ice a density of 0.9168 g cm^-3 at 0°C, whereas water has a density of 0.9998 g cm^-3 at 4 °C. A → water molecule consists of one → oxygen (O) atom bonded to two → hydrogen (H) atoms. The → specific heat of water, 1 calorie per gram per 1 degree C (cal/g/°C), is higher than most other substances. Therefore, water both absorbs and releases heat more slowly than land. This causes land areas to heat more rapidly and to higher temperatures and also cool more rapidly and to lower temperatures, compared to oceans. The high heat capacity of water also explains why the temperatures of land near a body of water are more moderate. The high heat capacity of water keeps its temperature within a relatively narrow range, causing nearby coastal areas to also have a narrow daily and seasonal temperature range. See also → heavy water, → ortho-water, → para-water.

Water, from O.E. wæter (cognates: Du. water; O.H.G. wazzar; Ger. Wasser; Goth. wato); cf. Gk. hydro-, combining form of hydor "water," cognate with Skt. udá- "water;" Khotanese ūtcā "water;" Hittite uātar; L. unda "wave;" O.C.S., Rus. voda; Lith. vanduo; from PIE base *wed- "water; wet."

Âb "water," variants iv, êw, âp; from Mid.Pers. âb "water;" O.Pers. ap- "water;" Av. ap- "water;" cf. Skt. áp- "water;" Hitt. happa- "water;" PIE āp-, ab- "water, river;" cf. Gk. Apidanos, proper noun, a river in Thessalia; L. amnis "stream, river" (from *abnis); O.Ir. ab "river," O.Prus. ape "stream," Lith. upé "stream;" Latv. upe "brook."

An ancient form of clock, used by several civilizations, consisting of a water container with a small hole from which the water slowly dripped. Time was reckoned by the level of the water remaining in the container.

→ water; → clock

Pang "a copper bason with a small hole in the bottom, for water in which it is placed to flow through, used for measuring time" used in Iran.

Water in the → solid state, produced by freezing → liquid water; frozen water. Ice forms at or below a temperature of 0°C. Ice is less dense than liquid water because it expands during the process of freezing. This is because the molecular arrangement taken by ice leads to an increase in volume and a decrease in density. → maximum density of water

→ water; → ice.

An interstellar → maser phenomenon in which water (H₂O) molecules undergo the processes of → population inversion and → stimulated emission. H₂O masers are detected toward star formation regions and the envelopes of evolved stars. The maser emission comes from regions that are typically quite small, not larger than the solar system. The main emission frequency is 22 GHz, which shows up in strong lines. There are, however, other H₂O maser transitions at 380 GHz and 183 GHz, which are much weaker than the 22 GHz line. The former transitions are sporadically detected since they are strongly absorbed in the Earth's atmosphere, because of its high water vapor content.

→ water; → maser

The chemical combination of one → oxygen (O) atom bonded to two → hydrogen (H) atoms. The bonding between the oxygen atom and each hydrogen atom is known as → covalent bonds. The two hydrogen atoms are bonded to the oxygen atom at a 105° angle. This geometry of the water molecule causes it to have positively and negatively changed ends, known as → polarity. Water is referred to a polar or dipolar molecule. The large nucleus of the oxygen atom attracts the shared electrons causing this side of the water molecule to be negatively charged while the hydrogen side is positively charged. This polarity allows water to bond easily with adjacent water molecules.

→ water; → molecule.

Same as → ocean planet.

→ water; → planet.

1) Water (H₂O) in the gaseous state.
2) Meteo.: Atmospheric water in vapor form; one of the most important components of the → atmosphere.

→ water; → vapor.

A spinning column of rising humid air that occurs over a body of warm water. Waterspouts fall within the class of atmospheric phenomena known as convective vortices that includes → tornadoes, → dust devils, and → hurricanes. They can feature wind speeds over 200 kilometers per hour.

→ water + spout, from M.E. spouten akin to M.Du. spiten "to spout;" O.E. spiwan "to spew."

Tanure-ye daryâyi, from tanuré (kešidan) "turning and raising in the air," probably from tanidan "to turn, spin," → tension; daryâyi, → marine.

A unit of power in the SI or MKS system of units, symbol W, equivalent to one joule per second. 1 W = 1 J s^-1 = 1 kg m² s^-3 = 1 N m s^-1 = 10⁷ erg s^-1.
Electricity: The current in amperes multiplied by the electrical potential in volts.

In honor of James Watt (1736-1819) the eminent Scottish inventor and mechanical engineer.

Unit of work or energy, equal to one watt for one hour, or 3.6 x 10¹⁰ ergs., or 3600 joules. The kilowatt-hour (kWh), i.e. 1,000 watts over the period of one hour, is the usual unit or measure of electricity supply or consumption. 1 kWh = 3.6 x 10⁶ J.

→ watt; → hour.