An Etymological Dictionary of Astronomy and Astrophysics

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.

Etymology (EN): 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.”

Etymology (PE): 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.