An Etymological Dictionary of Astronomy and Astrophysics

The point in a lunar orbit that is farthest from the center of the Lune. Also → apocynthion.

Etymology (EN): From → apo- “away from, off” + lune “moon,” from L. luna; PIE *louksnâ- “moon,” literally
“luminous, bright;”
compare with O.Pers. raucah-, 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”. The Mod.Pers. words rowšan, raxšân “bright, clear,” ruz “day,” foruq “light,” and afruxtan “to light, kindle” also belong to this family, as well as the E. light, Ger. Licht, and Fr. lumière.

Etymology (PE): Apâmah, apâmâh, → apocynthion.