fazâ-ye tondâyi, ~ tondâhâ
Fr.: espace de vitesses
Of a dynamical system, a three-dimensional space which consists of the set of values that the velocity can take (vx, vy, vz). → phase space.
Fr.: relation vitesse-distance
The linear relation wherein all galaxies are moving away from one another, with velocities that are greater with increasing distance of the galaxy. Same as → Hubble's law.
Fr.: veine contractée
L. vena "channel;" contracta, "contracted," → contract.
nemudâr-e Venn (#)
Fr.: diagramme de Venn
A schematic diagram using circles to represent sets and the relationships between them. Each circle represents one set. Two or more may be overlapped. The areas of overlap indicate subsets.
Named after John Venn (1834-1923), a British logician and philosopher, who introduced the diagram; → diagram.
The subterranean conduit from the underlying → magma chamber through which a volcano ejects igneous material. Same as volcanic vent.
M.E. venten "to furnish (a vessel) with a vent," from O.Fr. esventer "to air," from es-, → ex-, + venter, from vent, from L. ventus "wind."
Dudkaš "chimney," literally "smoke extractor," from dud, → smoke, + kaš "to extract, to draw," present stem of kešidan/kašidan "to carry, draw, protract, trail, drag" (Mid.Pers. kešidan "to draw, pull;" Av. karš- "to draw; to plow," karša- "furrow;" cf. Skt. kars-, kársati "to pull, drag, plow;" Gk. pelo, pelomai "to move, to bustle;" PIE base kwels- "to plow").
Fr.: débitmètre de Venturi, tube de ~
Named after Italian physicist Giovanni Battista Venturi (1746-1822); → tube
The second → planet from the → Sun, at a mean distance of roughly 108.21 × 106 km (0.72 → astronomical units). The → greatest elongation of Venus is about 47°, making it visible at most about 3 hours after sunset or before sunrise. Venus has the most circular orbit of any planet in the solar system. Venus is only slightly smaller than Earth (95% of Earth's diameter, 80% of Earth's mass). Its chemical composition and density are comparable to those of the Earth. It takes Venus just under 224.401 days to orbit the Sun, compared to the 365 day → orbital period of the Earth. Venus' rotation is → retrograde, that is it actually rotates from east to west, as opposed to west to east (→ prograde) which is the common rotating direction of most other planets. Seen from Venus, the sun would rise in the west and set in the east. Moreover, it takes about 244 Earth days for Venus to rotate once (→ sidereal rotation). This is longer than its orbital period. The length of its → solar day is about 117 Earth days. → Venus rotation. Its axial tilt is only three degrees, so there are no seasons on Venus. The → atmosphere on the surface of Venus consists mostly of → carbon dioxide, with a small trace of → nitrogen. Venus has a surface pressure about 90 times that of the Earth. See also: → Venus visibility, → transit of Venus.
O.E., from L. Venus, the goddess of beauty and love in ancient Roman mythology, from venus "love, sexual desire, beauty, charm;" PIE base *wen- "to desire, love, wish;" cf. Av. vāunuš "lovingly," vantā- "beloved one, wife;" Skt. van- "to love, desire," vanánā- "desire," vanitā- "beloved one, wife;" O.H.G. wunsc(h) "wish," wunsken "to wish."
Nâhid, planet Venus, Mid.Pers. Anahid; O.Pers. anāhita- "immaculate, unstained," goddess of pure waters and fertility, from Av. arədvī-sūra-anāhita "valient and unsustained lord of waters," from arədvī- (Skt. Saravastī) probably "she who possesses water," + sūra- "strong, powerful" (Skt. śūra- "valiant, courageous") + anāhita- "unstained," from an- negation prefix + āhita "spotted."
Fr.: rotation de Vénus
The → sidereal rotation period of Venus, or its → sidereal day, is 243.025 Earth days (retrograde). The length of a → solar day on Venus (that is one entire day-night period) is 116.75 Earth days, that is significantly shorter than the sidereal day because of the retrograde rotation. One Venusian year is about 1.92 Venusian solar days.
Fr.: visibilité de Vénus
The conditions under which Venus can be seen from Earth as
it travels in its orbit around the Sun.
The → synodic period of Venus, that is the time Venus takes to
be seen again from the
Earth in the same position with respect to the Sun, is 583,92 days
or just over 19 months. When Venus is between Earth and Sun
(→ inferior conjunction) or on the far side of the sun
(→ superior conjunction), it is invisible in the Sun's glare. Since its
→ greatest elongation
from the Sun is never more than 47°, Venus appears only as
"the morning star" and "the evening star."
So at its greatest → western elongation
Venus will rise about
three hours ahead of the Sun and at its greatest → eastern elongation
it will set about three hours after sunset.
Its entire cycle is as follows:
A member of a major category of words that refers to an action or a state. Verbs present a complex system of forms in Indo-European languages. The set of → inflectional forms of a verb is called a → conjugation. Verbs are usually distinguished for person and number along with tense and mood (if applicable).
M.E., from O.Fr. verbe from L. verbum "verb," originally "a word," from PIE root *wer- "to speak;" cf. Av. urvāta- "command;" Skt. vrata- "command, vow;" Gk. rhetor "public speaker," eirein "to speak, say;" Lith. vardas "name;" Goth. waurd, O.E. "word."
Karvâz, literally "action word," from kar- present stem of kardan "to do, make" (Mid.Pers. kardan; O.Pers./Av. kar- "to do, make, build," Av. kərənaoiti "he makes;" cf. Skt. kr- "to do, to make," krnoti "he makes, he does," karoti "he makes, he does," karma "act, deed;" PIE base kwer- "to do, to make") + vâz "word," variants vâž, âvâz, vâj, vât, vâ, → voice.
In exactly the same words; word for word.
From M.L. verbatim "word for word," from L. verbum "word," → verb.
Vâž-be-vâž, literally "word for word," from vâž, → word.
A measure of the convergence or divergence of a pair of light rays,
defined as the reciprocal of the distance between the point of focus
and a reference plane.
Gerâyi, from gerâyidan "to incline toward; to intend; to make for." Gerâ may be a variant of Mod.Pers. kil "bent, inclined" (k/g and l/r interchanges), from PIE base *klei- "to lean, incline," cognate with L. clinare "to bend" (E. declination, inclination, etc.), Gk. klinein "to cause to slope, slant, incline," Skt. sri- "to lean," O.Pers. θray-, Av. sray- "to lean," P.Gmc. *khlinen (Ger. lehnen, E. lean).
Fr.: principe de vérifiabilité
In logical positivism philosophy, the claim that a statement is literally meaningful (it expresses a proposition) if and only if it either actually has been verified or could at least in principle be verified.
The act of verifying. The state of being verified.
Verbal noun of → verify.
râst-jostan, râst-jost kardan
To ascertain the truth or correctness of, as by examination, research, or comparison.
M.E. verifien, from M.Fr. verifier, from M.L. verificare "to make true," from L. verus "true;" → -fy.
Râst-jostan, literally "to seek the truth, to seek the right," from râst "right, true; just, upright, straight" (Mid.Pers. râst "true, straight, direct;" Soghdian rəšt "right;" O.Pers. rāsta- "straight, true," rās- "to be right, straight, true;" Av. rāz- "to direct, put in line, set," razan- "order;" cf. Skt. raj- "to direct, stretch," rjuyant- "walking straight;" Gk. orektos "stretched out;" L. regere "to lead straight, guide, rule," p.p. rectus "right, straight;" PIE base *reg- "move in a straight line," hence, "to direct, rule") + jostan/juyidan "to seek, strive for" (Proto-Iranian *iud- "to struggle for something, to fight;" Av. yūδ- "to fight, struggle;" Mod.Pers. justan, juy- "to search, seek, ask for;" cf. Mid.Pers. vijuyihitan "to search, seek").
Of or pertaining to spring. → vernal equinox.
From L. vernalis "of the spring," from vernus "of spring," from uēr "spring," cognate with Pers. bahâr, as below.
Bahâri of or pertaining to bahâr "spring;" Mid.Pers. wahâr "spring;" O.Pers. vāhara- "spring time," θūra-vāhara- "name of a spring month;" Av. vaηhar "spring;" cf. Skt. vasara- "relating or appearing in the morning;" Gk. ear "spring;" L. uēr "spring," vernus "of spring;" O.N. vār "spring;" Lith. vasara "summer;" O.C.S. vesna "spring."
Fr.: équinoxe vernal
The point of intersection between the ecliptic and the celestial equator at which the Sun passes from south to north of the celestial equator during its apparent annual motion. The instant of this event. It occurs on March 20, 21 or rarely 19. At the vernal equinox, as with the → autumnal equinox, night and day are equal in length world over. Several thousands years ago the vernal equinox was in Aries, but because of precession it has now slid west into Pisces. Right ascension and celestial longitude are measured from the vernal equinox. Also known as spring equinox. → First Point of Aries.
sâl-e hamugân-e bahâri
Fr.: année d'équinoxe vernal, année vernale
The time interval between two successive passages of the Sun, when the true longitude of the Sun is considered. In other words, the interval during which the Sun's true longitude increases by 360 degrees. Its mean length for the epoch J2000.0 is 365.24236460 real solar days (approximately 365.2424 days). The vernal-equinox year, on which the Iranian calender is based, should not be confused with → tropical year. See also: A concise review of the Iranian calendar. → Iranian calendar
A small movable scale running parallel to the main graduated scale in certain measuring instruments, such as the → sextant, used to obtain a fractional reading of one of the divisions on the main scale. Also known as Vernier scale.
After the French mathematician Pierre Vernier (1580-1637), who invented the scale in 1631.