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Argand diagram nemudâr-e Argand Fr.: diagramme d'Argand A geometrical representation of → complex numbers, which like the → Cartesian coordinates, uses two reference perpendicular axes. The horizontal axis represents the → real number part of the number and the perpendicular axis the → imaginary number part. Named after Jean Robert Argand (1768-1822), a Swiss mathematician, who introduced this representation; → diagram. |
Argelander method raveš-e Argelander Fr.: méthode d'Argelander A technique to estimate the brightness of a → variable star. It involves comparing the variable with a sequence of neighboring stars of slightly different → magnitudes. Friedrich Wilhelm Argelander (1799-1875), German astronomer. His most important work was his compilation of the Bonner Durchmusterung; → method. |
Argo (Argo Navis; Ship Argo) Kašti (#) Fr.: Navire Argo An extensive constellation, one of the 48 constellations known to Greeks, representing the ship of Argonauts. It was divided in 18th century into the constellations → Carina, → Puppis, and → Vela. The ship in which Jason sailed in search of the Golden Fleece. Kašti "ship," from Mid.Pers. kaštik. |
argol lerd (#) Fr.: tartre A generally reddish matter that settles from a liquid, especially from wine. Same as → tartar. M.E. argul, argoile, from M.Fr. argoil, from L. argilla "argil." Lerd ou lert "the sediment of liquids, dregs, lees" (Dehxodâ). |
argon ârgon (#) Fr.: argon A → chemical element which occurs as a colorless, odorless, and tasteless gas in the atmosphere (of which it constitutes 0.94% by volume) and in some volcanic gases; symbol Ar. → Atomic number 18; → atomic weight 39.948; → melting point -189.2°C; → boiling points -185.7°C. Argon, from Gk. neutral of argos "inactive, idle, lazy," from negation prefix → a- + ergon "work," → energy. It was discovered in 1895 by the Scottish chemist William Ramsay and the English physicist Robert John Strutt (Lord Rayleigh) in liquified atmospheric air. |
argue âruzidan (#) Fr.: argumenter To put forth reasons for or against. → argument. |
argument âruzmân (#) Fr.: argument 1) General: A discussion involving differing points of view; debate;
a process of reasoning; series of reasons. M.E., from M.Fr., from L. argmentum, from arguere "to make clear." Compare with L. argentum "silver," Gk. argos "white," arguron "silver," Av. auruša- "white" (Mid.Pers. arus "white, bright"), Av. ərəzata- "silver," Skt. arjuna- "white, shining," rajata- "silver," Mod.Pers. arziz "silvery metal tin;" PIE *arg- "to shine, be white, bright, clear." Âruzmân, from Av. āroc- "to enlighten, make light," Av. raocah- "light, luminous; daylight;" Skt. roka- "brightness, light," cognate with Gk. leukos "white, clear;" L. lux "light" (also lumen, luna); PIE *leuk- "light, brightness" + noun forming suffix -mân. |
argument of periapsis âruzmân-e pirâhabâk Fr.: argument du périastre The angular distance between the → ascending node of an object orbiting a → primary and its periapsis measured from the primary. Argument of periapsis is measured in the → orbital plane in the direction of motion. It is one of the → orbital elements. See also → argument of perigee, → argument of perihelion. |
argument of perigee âruzmân-e pirâzam Fr.: argument du périgée The angular distance between the → ascending node of an object orbiting the Earth and its perigee, measured from the Earth. See also: → argument of perihelion, → argument of periapsis. |
argument of perihelion âruzmân-e pirâhur Fr.: argument du périhélie The angular distance between the → ascending node of an object orbiting the Sun and its perihelion. Argument of perihelion is measured in the → orbital plane with respect to the Sun and in the direction of motion. It is one of the → orbital elements and usually shown with the symbol ω. See also: → argument of perigee, → argument of periapsis. → argument; → perihelion. |
argumentation âruzeš Fr.: argumentation The presentation and elaboration of an argument or arguments. Noun from → argument. |
argumentative âruzmângin Fr.: raisonneur 1) Fond of or given to argument and dispute. |
arid kamâb (#) Fr.: aride Lacking sufficient water or rainfall. L. aridus, from arere "to be dry, i.e. burnt up"; compare with Gk. azaleos "dry," PIE *as- "to burn, glow". Kamâb, from Mod.P. kam "little, few, deficient, scarce" + âb "water". |
aridity kamâbi (#) Fr.: aridité A measure of the degree to which a climate lacks effective moisture. Aridity, noun from → arid. Kamâbi, noun from amâbi, → arid. |
Ariel (Uranus I) Ariel (#) Fr.: Ariel A satellite of → Uranus discovered by Lassell in 1851. It is orbiting at a mean distance of 192,000 kilometers with a period of 2.52 days. Ariel, a spirit in William Shakespeare's The Tempest. |
Aries Barré (#) Fr.: Bélier The Ram. A constellation of the → Zodiac,
representing a ram (R.A. = L. aries "ram," perhaps akin to Gk. eriphos "a kid, a young goat," O.Ir. heirp "she-goat;" cf. Lith. erytis, O.C.S. jarici, Arm. oroj "lamb." Barré "ram, sheep; Aries" from Mid.Pers. warrag "lamb,
ram; Aries," compare with Av. varənâ- "wool," Skt.
urana, urabhra "wool-beared = |
Aristarchus' inequality nâhamugi-ye Aristarchus Fr.: inégalité d'Aristarque Put in modern notation, if α and β are acute angles and if β <α, then sin α / sin β <α / β < tan α / tan β. Aristarchus probably used this inequality to show that the Sun is between 18 and 20 times as far from the Earth as the Moon is. Aristarchus of Samos (c.310-c.230 BC); → inequality. |
Aristotelian form dise-ye Arastuyi Fr.: forme aristotelienne Any of the four main → proposition
forms treated in Aristotle's → syllogism: Greek philosopher Aristotle (384-322 BC); → form. |
arithmetic hesâb (#) Fr.: arithmétique A branch of mathematics that deals usually with integers, rational numbers, real numbers, or complex numbers under addition, subtraction, multiplication, and division. See also → compute, → computation, → count, → calculate, → calculus, → mathematics, → statistics. O.Fr. arsmetique, from M.L. arithmetica, from Gk. arithmetike (tekhne) "(art, skill) of numbers," from arithmos "number." Hesâb, from Ar. hisab. |
arithmetic mean miyângin hesâbi (#) Fr.: moyenne arithmétique Of n numbers a_{1}, a_{2}, ..., a_{n}, the quantity defined as: (a_{1} + a_{2} + ... + a_{n})/n. → arithmetic; → mean. |
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