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

To put forth reasons for or against.

→ argument.

1) General: A discussion involving differing points of view; debate; a process of reasoning; series of reasons.
2a) Math.: The → independent variable of a → function.
2b) Math.: The → angle of a → complex number measured from the positive horizontal axis.
3) Astro.: → argument of periapsis, → argument of perigee, → argument of perihelion.
4a) Logic: A sequence of → propositions with one or more → premises and a → conclusion. Arguments are usually divided into two kinds, → deductive and → inductive.
4b) Logic: A → propositional symbol (→ variable or → constant) taken by a → predicate in an → atomic wff.

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.

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; → perigee.

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; → perigee.

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.

The presentation and elaboration of an argument or arguments.

Noun from → argument.

1) Fond of or given to argument and dispute.
2) Of or characterized by argument; controversial.

→ argue; → -ive

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".

A measure of the degree to which a climate lacks effective moisture.

Aridity, noun from → arid.

Kamâbi, noun from amâbi, → arid.

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.

The Ram. A constellation of the → Zodiac, representing a ram (R.A. = 2h 30m, Dec. = +13 deg). Its brightest star is → Hamal (α Arietis). Abbreviation: Ari; genitive form: Arietis.

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 = ram," from urna "wool," L. vervex "a wether, sheep".

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.

Any of the four main → proposition forms treated in Aristotle's → syllogism:
The A form (universal affirmative): All P's are Q's,
The E form (universal negative): No P's are Q's,
The I form (particular affirmative): Some P's are Q's, and
The O form (particular negative) Some P's are not Q's.

Greek philosopher Aristotle (384-322 BC); → form.

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.

Of n numbers a₁, a₂, ..., a_n, the quantity defined as: (a₁ + a₂ + ... + a_n)/n.

→ arithmetic; → mean.

A → sequence of n numbers or quantities such that the difference between any two successive terms is a constant. In particular, if a is the first term, the nth term is a + (n - 1)d, where d is the constant. Also called → arithmetic sequence.

→ arithmetic; → progression.

→ arithmetic progression.

→ arithmetic; → sequence.

1) Each of the upper limbs of the human body, especially the part between the → shoulder and the → wrist.
2) The upper limb from the shoulder to the → elbow.
3) A slender part of a structure projecting from a main part, such as a → spiral arm. → Orion Arm; → Perseus Arm; → Scutum-Crux Arm.

M.E. arm, from O.E. earm "arm," from P.Gmc. *armaz (cf. M.Du., Ger. Arm, O.N. armr, O.Fris. erm), from PIE base *ar- "to fit, join;" cf. Mod.Pers. arm, as below.

1) Ârm (Dehxodâ, Steingass) "arm, from the elbow to the shoulder;" Av. arma-, arəmo- "arm;" cf. Ossetic ärm "hand;" Armenian armuku "elbow;" Skt. irma- "arm;" Gk. arthron "a joint;" L. armus "shoulder;" cognate with E. arm, as above.
2) Bâzu, → upper arm.

An ancient instrument, used since ancient times until the Middle ages and later, to determine positions of celestial bodies. It consisted of an assemblage of rings, all circles of the same sphere, designed to represent the positions of the important circles of the celestial sphere.

L. armillarius, from armilla "arm ring, bracelet," from armus "arm" + → sphere.

Zâtolhelaq from Ar. "multi-ringed," from zât "holder, keeper" + helaq "rings," from halqah "ring."

1) An agreement between opposing armies to stop fighting for a particular time, especially in order to discuss possible peace; truce
2) A formal agreement, especially between nations, to end combat.

From Fr. armistice, from L. arma "arms" + -stitium, from sistere "to cause to stand," → solstice.

Nâjangân, literally "state of no war," from nâ- "no, not," → un-, + jang, → war, + -ân suffix of time and place.