An Etymological Dictionary of Astronomy and Astrophysics

To walk through water, snow, sand, or any other substance that impedes free motion or offers resistance to movement (Dictionary.com).

Etymology (EN): M.E. waden “to go, wade;” O.E. wadan “to go;” cf. Dan. vade, O.Fris. wada, Du. waden, Ger. waten, O.Norse vatha; akin to O.E. wæd “ford, sea,” L. vadere “to go, rush,” vadum “shoal, ford.”

Etymology (PE): Gampidan, related to Proto-Ir. *gamp-, *gamb- “to move,” cf. Dezfuli gomba, Bardesiri gopak “jump with two feet;” Sogd. (+ *â-) âγamp “walking;” (+ *uz-) Yighda žib-/žibi- “to rise, to stand,” jib- “to awake;” (+ *ham-) Wakhi gəfs-/gəfst- “to run.”

To walk through water, snow, sand, or any other substance that impedes free motion or offers resistance to movement (Dictionary.com).

Etymology (EN): M.E. waden “to go, wade;” O.E. wadan “to go;” cf. Dan. vade, O.Fris. wada, Du. waden, Ger. waten, O.Norse vatha; akin to O.E. wæd “ford, sea,” L. vadere “to go, rush,” vadum “shoal, ford.”

Etymology (PE): Gampidan, related to Proto-Ir. *gamp-, *gamb- “to move,” cf. Dezfuli gomba, Bardesiri gopak “jump with two feet;” Sogd. (+ *â-) âγamp “walking;” (+ *uz-) Yighda žib-/žibi- “to rise, to stand,” jib- “to awake;” (+ *ham-) Wakhi gəfs-/gəfst- “to run.”

1. The track left by a moving ship.
   

2. A turbulent region appearing behind an object in a fluid which streams around the object, for example behind an aircraft in flight.

Etymology (EN): Cognate with M.L.G. wake “wake,” Nor. dialect vok, O.N. vok, voka “hole in the ice.”

Etymology (PE): Kel, from Tabari kel, kal “trail, track, footprint.”

1. The track left by a moving ship.
   

2. A turbulent region appearing behind an object in a fluid which streams around the object, for example behind an aircraft in flight.

Etymology (EN): Cognate with M.L.G. wake “wake,” Nor. dialect vok, O.N. vok, voka “hole in the ice.”

Etymology (PE): Kel, from Tabari kel, kal “trail, track, footprint.”

1. To move along on foot at a moderate pace; advance by steps.
   

2a) An act or instance of walking.

2b) Physics: A moving of a particle among particles.
→ random walk; → quantum walk.

Etymology (EN): M.E. walken, from O.E. wealcan “to toss, roll;” cf. O.N. valka “to drag about,” Dan. valke “to full,” M.Du. walken “to knead, press, full,” O.H.G. walchan “to knead,” Ger. walken “to full.”

Etymology (PE): Camidan “to walk (proudly),” variant gâmidan “to walk,”
gâm “step, pace” (related to âmadan “to come,” → consequence); Mid.Pers. gâm “step, stride, pace;”
O.Pers. gam- “to come; to go;” Av. gam- “to come; to go,” jamaiti “goes;” cf. Skt. gamati “goes;” Gk. bainein “to go, walk, step;” L. venire “to come;” Tocharian A käm- “to come;” O.H.G. queman “to come;” E. come; PIE stem *g^wem- “to go, come.”
Puyeš, verbal noun of puyidan “to walk, run, trot; wander,” from Mid.Pers. pôy-, pwd- “to run;” cf. Gk. speudein “to hasten;” Lith. spudinti.

1. To move along on foot at a moderate pace; advance by steps.
   

2a) An act or instance of walking.

2b) Physics: A moving of a particle among particles.
→ random walk; → quantum walk.

Etymology (EN): M.E. walken, from O.E. wealcan “to toss, roll;” cf. O.N. valka “to drag about,” Dan. valke “to full,” M.Du. walken “to knead, press, full,” O.H.G. walchan “to knead,” Ger. walken “to full.”

Etymology (PE): Camidan “to walk (proudly),” variant gâmidan “to walk,”
gâm “step, pace” (related to âmadan “to come,” → consequence); Mid.Pers. gâm “step, stride, pace;”
O.Pers. gam- “to come; to go;” Av. gam- “to come; to go,” jamaiti “goes;” cf. Skt. gamati “goes;” Gk. bainein “to go, walk, step;” L. venire “to come;” Tocharian A käm- “to come;” O.H.G. queman “to come;” E. come; PIE stem *g^wem- “to go, come.”
Puyeš, verbal noun of puyidan “to walk, run, trot; wander,” from Mid.Pers. pôy-, pwd- “to run;” cf. Gk. speudein “to hasten;” Lith. spudinti.

1. An upright continuous structure that divides one area from another or surrounds an area.
   

   2. A wall-like, enclosing part, mass, or thing .

Etymology (EN): M.E., from O.E. w(e)all “rampart, dike, cliff,” also “defensive fortification around a city, side of a building” (O.Sax., O.Fris., M.L., M.Du. wal), from L. vallum “wall, rampart.”

Etymology (PE): Divâr “wall,” from Mid.Pers. dîvâr “wall;” related to Mid.Pers. bâr, var “enclosure, defences, fortress;” Mod.Pers. bâru “wall, rampart, fortification; fort; tower;” O.Pers. didā- “wall, stronghold, fortress;” Av. var- “castle,” from var- “to cover, conceil;” Proto-Iranian *dida-vāra-; cf. Skt. dehī- “wall;” Gk. teikhos “wall;” E. dike, ditch.

1. An upright continuous structure that divides one area from another or surrounds an area.
   

   2. A wall-like, enclosing part, mass, or thing .

Etymology (EN): M.E., from O.E. w(e)all “rampart, dike, cliff,” also “defensive fortification around a city, side of a building” (O.Sax., O.Fris., M.L., M.Du. wal), from L. vallum “wall, rampart.”

Etymology (PE): Divâr “wall,” from Mid.Pers. dîvâr “wall;” related to Mid.Pers. bâr, var “enclosure, defences, fortress;” Mod.Pers. bâru “wall, rampart, fortification; fort; tower;” O.Pers. didā- “wall, stronghold, fortress;” Av. var- “castle,” from var- “to cover, conceil;” Proto-Iranian *dida-vāra-; cf. Skt. dehī- “wall;” Gk. teikhos “wall;” E. dike, ditch.

A photometric system with five wavelength ranges that does not use
filters. Instead it uses prisms and lenses (spectroscopy) to select the bands simultaneously. The wavelengths and the bandwidths are: W, 3250 and 140 Å; U, 3630 and 240 Å; L, 3840 and 230 Å; B, 4320 and 450 Å; and V, 5470 and 720 Å. The Walraven photometer was unique in design and remained literally unique as copies were never built. In addition, during its whole life the photometer was mounted permanently on the same telescope that had been built specifically for this instrument, the 91 cm Lightcollector’ reflector, which started in 1958 at the Leiden Southern Station in Broederstroom, South-Africa. After 20 years in South-Africa the telescope and photometer were moved to the European Southern Observatory La Silla observatory in Chile. The photometric observations were resumed in March 1979 and continued for another 12 years until the decommissioning of the photometer in 1991.

See also: After the inventors, the Dutch astronomer Theodore Walraven (1916-) and his wife Johanna Helena Walraven, née Terlinden (1920-89); → photometry.

A photometric system with five wavelength ranges that does not use
filters. Instead it uses prisms and lenses (spectroscopy) to select the bands simultaneously. The wavelengths and the bandwidths are: W, 3250 and 140 Å; U, 3630 and 240 Å; L, 3840 and 230 Å; B, 4320 and 450 Å; and V, 5470 and 720 Å. The Walraven photometer was unique in design and remained literally unique as copies were never built. In addition, during its whole life the photometer was mounted permanently on the same telescope that had been built specifically for this instrument, the 91 cm Lightcollector’ reflector, which started in 1958 at the Leiden Southern Station in Broederstroom, South-Africa. After 20 years in South-Africa the telescope and photometer were moved to the European Southern Observatory La Silla observatory in Chile. The photometric observations were resumed in March 1979 and continued for another 12 years until the decommissioning of the photometer in 1991.

See also: After the inventors, the Dutch astronomer Theodore Walraven (1916-) and his wife Johanna Helena Walraven, née Terlinden (1920-89); → photometry.

Decreasing in strength, intensity, power, etc.

Etymology (EN): Waning, from wane, from M.E. wanen (v.), O.E. wanian “to lessen;” cf. O.S. wanon, O.N. vana, O.Fris. wania, M.Du. waenen, O.H.G. wanon “to wane, to grow less.”

Etymology (PE): Kâhandé “waning, decreasing;” from kâstan, kâhidan “to decrease;” Mid.Pers. kâhitan, kâstan, kâhênitan “to decrease, diminish, lessen;” Av. kasu- “small, little” (Mod.Pers. keh); Proto-Iranian *kas- “to be small, diminish, lessen.”

Decreasing in strength, intensity, power, etc.

Etymology (EN): Waning, from wane, from M.E. wanen (v.), O.E. wanian “to lessen;” cf. O.S. wanon, O.N. vana, O.Fris. wania, M.Du. waenen, O.H.G. wanon “to wane, to grow less.”

Etymology (PE): Kâhandé “waning, decreasing;” from kâstan, kâhidan “to decrease;” Mid.Pers. kâhitan, kâstan, kâhênitan “to decrease, diminish, lessen;” Av. kasu- “small, little” (Mod.Pers. keh); Proto-Iranian *kas- “to be small, diminish, lessen.”

The crescent phase of the Moon following the → last quarter which finally disappears with setting Sun.

See also: → waning; → crescent.

The crescent phase of the Moon following the → last quarter which finally disappears with setting Sun.

See also: → waning; → crescent.

The oval shape of the moon a few days after the → full moon and before the → last quarter.

See also: → waning; → gibbous.

The oval shape of the moon a few days after the → full moon and before the → last quarter.

See also: → waning; → gibbous.

The circumstance when the phase of the Moon is decreasing from → full moon to → new moon.

See also: → waning; → moon.

The circumstance when the phase of the Moon is decreasing from → full moon to → new moon.

See also: → waning; → moon.

A state of armed conflict between states, or between groups within states.

Etymology (EN): From M.E. werre, from O.E. werre, wyrre, from Old Northern Fr. werre, akin to O.H.G. werra “confusion, strife, quarrel,” Du. war “confusion, disarray,” O.E. wyrsa, wiersa “worse,” O.Norse verri “worse; confounded;” ultimately from PIE *wers- “to confuse, mix up.”

Etymology (PE): Jang, from Mid.Pers. jang “struggle, battle, fight.”

A state of armed conflict between states, or between groups within states.

Etymology (EN): From M.E. werre, from O.E. werre, wyrre, from Old Northern Fr. werre, akin to O.H.G. werra “confusion, strife, quarrel,” Du. war “confusion, disarray,” O.E. wyrsa, wiersa “worse,” O.Norse verri “worse; confounded;” ultimately from PIE *wers- “to confuse, mix up.”

Etymology (PE): Jang, from Mid.Pers. jang “struggle, battle, fight.”

Moderately hot.

Etymology (EN): M.E.; O.E. wearm (cf. O.S., O.Fris., M.Du., O.H.G., Ger. warm, O.N. varmr, Goth. warmjan “to warm”); cognate with Pers. garm, as below.

Etymology (PE): Garm “warm;” Mid.Pers. garm “warm;” O.Pers. garma-pada “name of the fourth month” (June-July); Av. garəma- “warm; heat;” cf. Skt. gharmá “heat;” Gk. therme, thermos; L. formus “warm;” E. warm, as above; PIE base *ghworm-/*ghwerm- “warm.”

Moderately hot.

Etymology (EN): M.E.; O.E. wearm (cf. O.S., O.Fris., M.Du., O.H.G., Ger. warm, O.N. varmr, Goth. warmjan “to warm”); cognate with Pers. garm, as below.

Etymology (PE): Garm “warm;” Mid.Pers. garm “warm;” O.Pers. garma-pada “name of the fourth month” (June-July); Av. garəma- “warm; heat;” cf. Skt. gharmá “heat;” Gk. therme, thermos; L. formus “warm;” E. warm, as above; PIE base *ghworm-/*ghwerm- “warm.”

A cloud of ionized gas within → active galactic nuclei (AGN) that causes absorption at → soft X-ray wavelengths. Warm absorbers were first suggested by Halpern (1984) to explain Einstein data of the quasar MR 2251-178. They are dubbed “warm” absorbers as they imply gas at temperatures of 10⁴-10⁵ K; the gas is → photoionized, not collisionally ionized. High resolution observations of warm absorbers have shown that they are outfowing. See also → cold absorber
(Ceri Ellen Ashton, 2005, A Study of Warm Absorbers in Active Galactic Nuclei, Thesis, Mullard Space Science Laboratory Department of Space and Climate Physics University College London ).

See also: → warm; → absorber.

A cloud of ionized gas within → active galactic nuclei (AGN) that causes absorption at → soft X-ray wavelengths. Warm absorbers were first suggested by Halpern (1984) to explain Einstein data of the quasar MR 2251-178. They are dubbed “warm” absorbers as they imply gas at temperatures of 10⁴-10⁵ K; the gas is → photoionized, not collisionally ionized. High resolution observations of warm absorbers have shown that they are outfowing. See also → cold absorber
(Ceri Ellen Ashton, 2005, A Study of Warm Absorbers in Active Galactic Nuclei, Thesis, Mullard Space Science Laboratory Department of Space and Climate Physics University College London ).

See also: → warm; → absorber.

Meteo.: A leading edge that advances in a mass of air and replaces cooler air by warm air.

See also: → warm; → front.

Meteo.: A leading edge that advances in a mass of air and replaces cooler air by warm air.

See also: → warm; → front.

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.

See also: → warm; → intercloud medium.

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.

See also: → 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.

See also: → warm; → hot; → intergalactic 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.

See also: → warm; → hot; → intergalactic medium.

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

See also: → warm; → -ing.

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

See also: → 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.

Etymology (EN): 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.”

Etymology (PE): 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.”

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.

Etymology (EN): 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.”

Etymology (PE): 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.

See also: → warp; → disk.

A → galactic disk that exhibits a → warp phenomenon.

See also: → 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.

See also: Verbal noun from → warp (v.).

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.

See also: 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).

Etymology (EN): 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.”

Etymology (PE): 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).”

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

Etymology (EN): 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.”

Etymology (PE): 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.

Etymology (EN): 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.

Etymology (PE): 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).

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

Etymology (EN): 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.

Etymology (PE): 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).

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

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).

See also: 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.

Etymology (EN): M.E., from O.Fr. wast, g(u)ast, from L. vastum, neuter of vastus “waste.”

Etymology (PE): Âxâl “waste, rubbish,” of unknown origin.

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

Etymology (EN): M.E., from O.Fr. wast, g(u)ast, from L. vastum, neuter of vastus “waste.”

Etymology (PE): 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.

Etymology (EN): 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.”

Etymology (PE): 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.”

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.

Etymology (EN): 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.”

Etymology (PE): 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.

Etymology (EN): → water; → clock

Etymology (PE): 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.

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.

Etymology (EN): → water; → clock

Etymology (PE): 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

See also: → water; → ice.

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

See also: → 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.

See also: → water; → maser

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.

See also: → 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.

See also: → water; → molecule.

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.

See also: → water; → molecule.

Same as → ocean planet.

See also: → water; → planet.

Same as → ocean planet.

See also: → 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.

See also: → water; → vapor.

1. Water (H₂O) in the gaseous state.
   

2. Meteo.: Atmospheric water in vapor form; one of the most important components of the → atmosphere.

See also: → 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.

Etymology (EN): → water + spout, from
M.E. spouten akin to M.Du. spiten “to spout;” O.E. spiwan “to spew.”

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

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.

Etymology (EN): → water + spout, from
M.E. spouten akin to M.Du. spiten “to spout;” O.E. spiwan “to spew.”

Etymology (PE): 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.

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

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.

See also: 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.

See also: → watt; → hour.

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.

See also: → watt; → hour.

A fleshy lobe or appendage hanging down from the throat or chin of certain birds, as the domestic chicken or turkey (Dictionary.com).

Etymology (EN): Of uncertain origin.

Etymology (PE): Jil (in Nâini and Baxtiyâri) “wattle.”

A fleshy lobe or appendage hanging down from the throat or chin of certain birds, as the domestic chicken or turkey (Dictionary.com).

Etymology (EN): Of uncertain origin.

Etymology (PE): Jil (in Nâini and Baxtiyâri) “wattle.”

An instrument used for measuring the magnitude of the power in an electric circuit.

See also: → watt; → -meter.

An instrument used for measuring the magnitude of the power in an electric circuit.

See also: → watt; → -meter.

1. General: A raised ridge-shaped formation moving across the surface of a liquid (as of the sea).
   

2. Physics: A disturbance advancing from point to point in a → medium or → space as in the → propagation of → sound or → light.
   

See also:
→ acoustic wave, → acoustic wave equation, → advanced wave, → Alfven wave, → ballistic wave, → blaze wavelength, → bow wave, → collapse of the wave function, → complex wave, → compressional wave, → cosmic microwave background anisotropy, → cosmic microwave background radiation, → decimetric wave, → density wave, → density-wave theory, → elastic wave, → electromagnetic wave, → electrostatic wave, → gravitational wave, → gravity wave, → half-wave plate, → heat wave, → incoherent wave, → Langmuir wave, → longitudinal wave, → Mach wave, → microwave, → microwave background radiation, → microwave radiation, → millimeter wave, → millimeter-wave astronomy, → modulated wave, → Moreton wave, → neutral wave, → P-wave, → periodic wave, → plane wave, → quarter-wave plate, → radio wave, → rarefaction wave, → retarded wave, → Rossby wave, → S-wave, → scalar wave, → seismic wave, → Shack-Hartmann wavefront sensor, → shear wave, → shock wave, → sine wave, → sound wave, → square wave, → standing wave, → stationary wave, → submillimeter wave, → transverse wave, → wave equation, → wave function, → wave mechanics, → wave nature, → wave numbe, → wave optics, → wave packet, → wave plate, → wave theory of light, → wave vector, → wave-particle duality, → waveband, → waveform , → waveform analysis, → wavefront, → wavefront correction, → wavefront distortion, → wavefront sensor, → wavefront tilt, → waveguide, → wavelength, → wavelet, → wavelet theory, → wave train.

Etymology (EN): M.E. waw; O.E. wagian “to move to and fro,” wafian “to wave with the hands” (cf. O.N. vafra “to hover about,” M.H.G. waben “to wave, undulate”).

Etymology (PE): Mowj, loan from Ar. mauj.

1. General: A raised ridge-shaped formation moving across the surface of a liquid (as of the sea).
   

2. Physics: A disturbance advancing from point to point in a → medium or → space as in the → propagation of → sound or → light.
   

See also:
→ acoustic wave, → acoustic wave equation, → advanced wave, → Alfven wave, → ballistic wave, → blaze wavelength, → bow wave, → collapse of the wave function, → complex wave, → compressional wave, → cosmic microwave background anisotropy, → cosmic microwave background radiation, → decimetric wave, → density wave, → density-wave theory, → elastic wave, → electromagnetic wave, → electrostatic wave, → gravitational wave, → gravity wave, → half-wave plate, → heat wave, → incoherent wave, → Langmuir wave, → longitudinal wave, → Mach wave, → microwave, → microwave background radiation, → microwave radiation, → millimeter wave, → millimeter-wave astronomy, → modulated wave, → Moreton wave, → neutral wave, → P-wave, → periodic wave, → plane wave, → quarter-wave plate, → radio wave, → rarefaction wave, → retarded wave, → Rossby wave, → S-wave, → scalar wave, → seismic wave, → Shack-Hartmann wavefront sensor, → shear wave, → shock wave, → sine wave, → sound wave, → square wave, → standing wave, → stationary wave, → submillimeter wave, → transverse wave, → wave equation, → wave function, → wave mechanics, → wave nature, → wave numbe, → wave optics, → wave packet, → wave plate, → wave theory of light, → wave vector, → wave-particle duality, → waveband, → waveform , → waveform analysis, → wavefront, → wavefront correction, → wavefront distortion, → wavefront sensor, → wavefront tilt, → waveguide, → wavelength, → wavelet, → wavelet theory, → wave train.

Etymology (EN): M.E. waw; O.E. wagian “to move to and fro,” wafian “to wave with the hands” (cf. O.N. vafra “to hover about,” M.H.G. waben “to wave, undulate”).

Etymology (PE): Mowj, loan from Ar. mauj.

In the → Copenhagen Interpretation of → quantum mechanics,
the change undergone by the → wave function of a particle when a measurement is performed on the particle. The wave function collapses to one that has a definite value for the quantity measured. If the → position of the matter wave is measured, it collapses to a localized → pulse. If → momentum is measured, it collapses to a wave with a definite momentum. Same as → collapse of the wave function.

See also: → wave; → collapse.

In the → Copenhagen Interpretation of → quantum mechanics,
the change undergone by the → wave function of a particle when a measurement is performed on the particle. The wave function collapses to one that has a definite value for the quantity measured. If the → position of the matter wave is measured, it collapses to a localized → pulse. If → momentum is measured, it collapses to a wave with a definite momentum. Same as → collapse of the wave function.

See also: → wave; → collapse.

The partial differential equation

∂²U / ∂²x + ∂²U / ∂²y + ∂²U / ∂²z = (1/c²) ∂²U / ∂²t
or its counterparts in one or two dimensions or in other coordinates,
the solution of which represents the propagation of displacementU as waves with velocity c.

See also: → wave; → equation.

The partial differential equation

∂²U / ∂²x + ∂²U / ∂²y + ∂²U / ∂²z = (1/c²) ∂²U / ∂²t
or its counterparts in one or two dimensions or in other coordinates,
the solution of which represents the propagation of displacementU as waves with velocity c.

See also: → wave; → equation.

In → quantum mechanics, the function of space and time that satisfies → Schrodinger equation.
The square of the modulus of its amplitude at any point represents the probability of finding a particle there.

See also: → wave; → function.

In → quantum mechanics, the function of space and time that satisfies → Schrodinger equation.
The square of the modulus of its amplitude at any point represents the probability of finding a particle there.

See also: → wave; → function.

One of the forms of quantum mechanics, due to Louis de Broglie and extended by E. Schrödinger. It originated in the suggestion that light consists of corpuscles as well as of waves and the consequent suggestion that all elementary particles are associated with waves.

See also: → wave; → mechanics

One of the forms of quantum mechanics, due to Louis de Broglie and extended by E. Schrödinger. It originated in the suggestion that light consists of corpuscles as well as of waves and the consequent suggestion that all elementary particles are associated with waves.

See also: → wave; → mechanics

A general term to describe → light involving the following phenomena:
→ reflection, → refraction, → interference, → diffraction, and → polarization. Compare → particle nature.

See also: → wave; → nature.

A general term to describe → light involving the following phenomena:
→ reflection, → refraction, → interference, → diffraction, and → polarization. Compare → particle nature.

See also: → wave; → nature.

The reciprocal of → wavelength, which represents the number of waves per unit length. Wave number is often defined as k = 2π/λ. Same as → propagation number.

See also: → wave; → number

The reciprocal of → wavelength, which represents the number of waves per unit length. Wave number is often defined as k = 2π/λ. Same as → propagation number.

See also: → wave; → number

The branch of optics that analyzes the electromagnetic radiation in terms of its wave characteristics. Also called → physical optics.

See also: → wave; → optics.

The branch of optics that analyzes the electromagnetic radiation in terms of its wave characteristics. Also called → physical optics.

See also: → wave; → optics.

A traveling → waveform consisting of the → superposition of several → waves of different → wavelengths and → phases.

Etymology (EN): → wave; packet from M.E. pak “bundle” + diminutive suffix -et; maybe from M.Fr. pacquet.

Etymology (PE): Basté “packet,” literally “bound, tied; set,” p.p. of bastan “to form, bind, tie” (Mid.Pers. bastan/vastan “to bind, shut;” Av./O.Pers. band- “to bind, fetter,” banda- “band, tie;” cf. Skt. bandh- “to bind, tie, fasten;” Ger. binden; E. bind; PIE base *bhendh- “to bind”).

A traveling → waveform consisting of the → superposition of several → waves of different → wavelengths and → phases.

Etymology (EN): → wave; packet from M.E. pak “bundle” + diminutive suffix -et; maybe from M.Fr. pacquet.

Etymology (PE): Basté “packet,” literally “bound, tied; set,” p.p. of bastan “to form, bind, tie” (Mid.Pers. bastan/vastan “to bind, shut;” Av./O.Pers. band- “to bind, fetter,” banda- “band, tie;” cf. Skt. bandh- “to bind, tie, fasten;” Ger. binden; E. bind; PIE base *bhendh- “to bind”).

An optical element that retards the phase of one plane of vibration of light relative to the plane at right angles. The two beams then recombine to form a single beam with new polarization characteristics. A typical wave plate is a birefringent crystal with a carefully chosen orientation and thickness. Also known as → retardation plate. A → half-wave plate creates a half-wave retardation. See also → quarter-wave plate.

See also: → wave; → plate.

An optical element that retards the phase of one plane of vibration of light relative to the plane at right angles. The two beams then recombine to form a single beam with new polarization characteristics. A typical wave plate is a birefringent crystal with a carefully chosen orientation and thickness. Also known as → retardation plate. A → half-wave plate creates a half-wave retardation. See also → quarter-wave plate.

See also: → wave; → plate.

The theory that describes light as waves that spread out from the source that generates the light. It contradicts the → corpuscular theory of light proposed by Newton (1704). The idea of the wave nature of light was first put forward by Robert Hooke (1660). The wave theory was originally stated by Huygens (1690), who showed reflection and refraction could be explained by this theory. It was supported by → Young’s experiment (1802) and established by the work of Fresnel (1814-1815). The wave theory received its most important support from Maxwell’s → electromagnetic theory. See also → Huygens-Fresnel principle.

See also: → wave; → theory; → light.

The theory that describes light as waves that spread out from the source that generates the light. It contradicts the → corpuscular theory of light proposed by Newton (1704). The idea of the wave nature of light was first put forward by Robert Hooke (1660). The wave theory was originally stated by Huygens (1690), who showed reflection and refraction could be explained by this theory. It was supported by → Young’s experiment (1802) and established by the work of Fresnel (1814-1815). The wave theory received its most important support from Maxwell’s → electromagnetic theory. See also → Huygens-Fresnel principle.

See also: → wave; → theory; → light.

A series of successive waves spaced at regular intervals.

See also: → wave; → train.

A series of successive waves spaced at regular intervals.

See also: → wave; → train.

A vector whose direction is that of propagation of a wave and whose magnitude is given by the → wave number, 2π/λ, where λ is the → wavelength, or ω/c, where ω is the → angular frequency and c is the speed of propagation.

See also: → wave; → number.

A vector whose direction is that of propagation of a wave and whose magnitude is given by the → wave number, 2π/λ, where λ is the → wavelength, or ω/c, where ω is the → angular frequency and c is the speed of propagation.

See also: → wave; → number.

The principle admitted in → quantum mechanics that all particles have a wave-like nature and that waves have a particle aspect. The wave-particle duality is of fundamental importance in obtaining a realistic picture of the → elementary particles.

See also: → particle nature, → wave nature, → de Broglie hypothesis, → Davisson-Germer experiment.

See also: → wave; → particle; → duality.

The principle admitted in → quantum mechanics that all particles have a wave-like nature and that waves have a particle aspect. The wave-particle duality is of fundamental importance in obtaining a realistic picture of the → elementary particles.

See also: → particle nature, → wave nature, → de Broglie hypothesis, → Davisson-Germer experiment.

See also: → wave; → particle; → duality.

A portion of the electromagnetic spectrum which is defined because of its characteristics or for its use.

See also: → wave; → band.

A portion of the electromagnetic spectrum which is defined because of its characteristics or for its use.

See also: → wave; → band.

A graphical representation of the shape of a wave for a given instant in time.

See also: → wave; → form.

A graphical representation of the shape of a wave for a given instant in time.

See also: → wave; → form.

The resolution of a complex waveform into a sum of simple periodic waves, usually by computer means.

See also: → waveform; → analysis.

The resolution of a complex waveform into a sum of simple periodic waves, usually by computer means.

See also: → waveform; → analysis.

The locus of adjacent points possessing the same phase in the path of a wave motion. Its surface is uniform (spherical or plane) and normal to propagation direction in an isotropic medium. → wavefront distortion.

See also: → wave; → front.

The locus of adjacent points possessing the same phase in the path of a wave motion. Its surface is uniform (spherical or plane) and normal to propagation direction in an isotropic medium. → wavefront distortion.

See also: → wave; → front.

In → adaptive optics, eliminating the effects of atmospheric turbulence on the wavefront of the object being observed. → wavefront distortion.

See also: → wavefront; → correction.

In → adaptive optics, eliminating the effects of atmospheric turbulence on the wavefront of the object being observed. → wavefront distortion.

See also: → wavefront; → correction.

The disruption of the spherical shape of a wavefront due to atmospheric turbulence which makes the adjacent points in the wavefront out of phase.

See also: → wavefront; → distortion.

The disruption of the spherical shape of a wavefront due to atmospheric turbulence which makes the adjacent points in the wavefront out of phase.

See also: → wavefront; → distortion.

In adaptive optics, a device that analyzes the light sample coming from the wavefront and determines the error in each part of the beam. The wavefront sensor used in adaptive optics is a → Shack-Hartmann type, which works in conjunction with a deformable mirror.

See also: → wavefront; → sensor.

In adaptive optics, a device that analyzes the light sample coming from the wavefront and determines the error in each part of the beam. The wavefront sensor used in adaptive optics is a → Shack-Hartmann type, which works in conjunction with a deformable mirror.

See also: → wavefront; → sensor.

The average slope in both the X and Y directions of a → wavefront or phase profile across the pupil of an optical system.

See also: → wavefront; → tilt.

The average slope in both the X and Y directions of a → wavefront or phase profile across the pupil of an optical system.

See also: → wavefront; → tilt.

Any transmission medium, such as a hollow metal conductor, coaxial cable, or glass fiber, capable of confining and supporting the propagation of electromagnetic waves regardless of wavelength or mode of propagation.

Etymology (EN): → wave; guide, M.E., from O.Fr. guider “to guide, lead,” from Frankish *witan “show the way,” from P.Gmc. *wit- “to know” (cf. Ger. weisen “to show, point out,” wissen “to know;” O.E. witan “to see”). Cognate with Pers. bin- “to see” (present stem of didan “to see”); Mid.Pers. wyn-;
O.Pers. vain- “to see;” Av. vaēn- “to see;”
Skt. veda “I know;” Gk. oida “I know,” idein “to see;” L. videre “to see;” PIE base *weid- “to know, to see.”

Etymology (PE): Mowjbar, from mowj, → wave, + -bar “carrier,” from bordan “to carry, lead” (Mid.Pers. burdan,
O.Pers./Av. bar- “to bear, carry,” barəθre “to bear (infinitive),” Skt. bharati “he carries,” Gk. pherein, L. fero “to carry;” PIE base *bher- “to carry”).

Any transmission medium, such as a hollow metal conductor, coaxial cable, or glass fiber, capable of confining and supporting the propagation of electromagnetic waves regardless of wavelength or mode of propagation.

Etymology (EN): → wave; guide, M.E., from O.Fr. guider “to guide, lead,” from Frankish *witan “show the way,” from P.Gmc. *wit- “to know” (cf. Ger. weisen “to show, point out,” wissen “to know;” O.E. witan “to see”). Cognate with Pers. bin- “to see” (present stem of didan “to see”); Mid.Pers. wyn-;
O.Pers. vain- “to see;” Av. vaēn- “to see;”
Skt. veda “I know;” Gk. oida “I know,” idein “to see;” L. videre “to see;” PIE base *weid- “to know, to see.”

Etymology (PE): Mowjbar, from mowj, → wave, + -bar “carrier,” from bordan “to carry, lead” (Mid.Pers. burdan,
O.Pers./Av. bar- “to bear, carry,” barəθre “to bear (infinitive),” Skt. bharati “he carries,” Gk. pherein, L. fero “to carry;” PIE base *bher- “to carry”).

The distance between two successive points in the wave that are characterized by the same phase of oscillation; e.g. → de Broglie wavelength; → Compton wavelength; → blaze wavelength; → peak wavelength; → center wavelength; → central wavelength; → cutoff wavelength.

See also: → wave; → length.

The distance between two successive points in the wave that are characterized by the same phase of oscillation; e.g. → de Broglie wavelength; → Compton wavelength; → blaze wavelength; → peak wavelength; → center wavelength; → central wavelength; → cutoff wavelength.

See also: → wave; → length.

A small wave; ripple.

See also: → wave + -let a diminutive suffix.

A small wave; ripple.

See also: → wave + -let a diminutive suffix.

A refinement of → Fourier analysis which enables to simplify the description of a complicated function in terms of a small number of coefficients.
The formal history of wavelet theory began in the early 1980s when Jean Morlet, a French geophysicist, introduced the concept of wavelet and studied wavelet transform as a new tool for scientific signal analysis. In 1984, his collaboration with Alex Grossmann yielded a detailed mathematical study of the continuous wavelet transforms and their various applications. Although similar results had already been obtained 20-50 years earlier by several other researchers, the rediscovery of the old concepts provided a new method for decomposing functions.

See also: → wavelet; → theory.

A refinement of → Fourier analysis which enables to simplify the description of a complicated function in terms of a small number of coefficients.
The formal history of wavelet theory began in the early 1980s when Jean Morlet, a French geophysicist, introduced the concept of wavelet and studied wavelet transform as a new tool for scientific signal analysis. In 1984, his collaboration with Alex Grossmann yielded a detailed mathematical study of the continuous wavelet transforms and their various applications. Although similar results had already been obtained 20-50 years earlier by several other researchers, the rediscovery of the old concepts provided a new method for decomposing functions.

See also: → wavelet; → theory.

1. A substance that is secreted by bees and is used by them for constructing the honeycomb, that is a dull yellow solid plastic when warm, and that is composed of a mixture of esters, cerotic acid, and hydrocarbons; called also beeswax.
   

2. Any of various substances resembling the wax of bees (Merriam-Webster.com).

Etymology (EN): M.E. waxen, O.E. weaxan; cognate with Du. was, Ger. Wachs.

Etymology (PE): Mum “wax; wax-candle.”

1. A substance that is secreted by bees and is used by them for constructing the honeycomb, that is a dull yellow solid plastic when warm, and that is composed of a mixture of esters, cerotic acid, and hydrocarbons; called also beeswax.
   

2. Any of various substances resembling the wax of bees (Merriam-Webster.com).

Etymology (EN): M.E. waxen, O.E. weaxan; cognate with Du. was, Ger. Wachs.

Etymology (PE): Mum “wax; wax-candle.”

Increasing in extent, quantity, intensity, power, etc.

Etymology (EN): Waxing, from wax, from M.E. wax “to grow bigger, greater;” O.E. weaxan “to increase, grow;” cf. O.H.G. wahsan, O.N. vaxa, Du. wassen, Ger. wachsen “to grow, increase;” cognate with Mid.Pers. waxš-, waxšidan “to grow;” Av. xaxš- “to grow,” xaxša- “growth;” Skt. vaks- “to grow, become big;” Gk. auxein “to increase.”

Etymology (PE): Fazâyandé “waxing, incresing,” from fozudan, variant of afzudan “to add, increase” (Mid.Pers. abzudan “to increase, grow;” O.Pers. abijav- “to increase, add to, promote,” from abi-, aiby- “in addition to; to; against” + root jav- “press forward;” Av. gav- “to hasten, drive;” Sk. jav- “to press forward, impel quickly, excite,” javate “hastens”).

Increasing in extent, quantity, intensity, power, etc.

Etymology (EN): Waxing, from wax, from M.E. wax “to grow bigger, greater;” O.E. weaxan “to increase, grow;” cf. O.H.G. wahsan, O.N. vaxa, Du. wassen, Ger. wachsen “to grow, increase;” cognate with Mid.Pers. waxš-, waxšidan “to grow;” Av. xaxš- “to grow,” xaxša- “growth;” Skt. vaks- “to grow, become big;” Gk. auxein “to increase.”

Etymology (PE): Fazâyandé “waxing, incresing,” from fozudan, variant of afzudan “to add, increase” (Mid.Pers. abzudan “to increase, grow;” O.Pers. abijav- “to increase, add to, promote,” from abi-, aiby- “in addition to; to; against” + root jav- “press forward;” Av. gav- “to hasten, drive;” Sk. jav- “to press forward, impel quickly, excite,” javate “hastens”).

The phase of the Moon between the → new moon and the → first quarter which first appears in the evening.

See also: → waxing; → crescent.

The phase of the Moon between the → new moon and the → first quarter which first appears in the evening.

See also: → waxing; → crescent.

The oval shape of the Moon a few days after the → first quarter.

See also: → waxing; → gibbous.

The oval shape of the Moon a few days after the → first quarter.

See also: → waxing; → gibbous.

The circumstance when the phase of the Moon is increasing from → new moon to → full moon.

See also: → waxing; → moon.

The circumstance when the phase of the Moon is increasing from → new moon to → full moon.

See also: → waxing; → moon.

A road, track, or path.

Etymology (EN): M.E. wei(gh)e, wai, from
O.E. weg “road, path;” cf. Du. weg, O.H.G. weg, Ger. Weg, Goth. wigs “way;” PIE base *wegh- “to move.”

Etymology (PE): 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”);

A road, track, or path.

Etymology (EN): M.E. wei(gh)e, wai, from
O.E. weg “road, path;” cf. Du. weg, O.H.G. weg, Ger. Weg, Goth. wigs “way;” PIE base *wegh- “to move.”

Etymology (PE): 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”);