type of precious stone, late 14c., from Latin selenites, from Greek selēnitēs "moonstone," literally "of the moon" (in lithos selēnitēs), from selēnē "moon" (see Selene). Said to be so called for its coloring or for its supposed waxing and waning with the moon.
"hold a second job, especially at night," 1957 (implied in the verbal noun moonlighting), from moonlighter "one who takes a second job after hours" (1954), from the notion of working by the light of the moon; see moonlight (n.). Earlier the verb had been used to mean "commit crimes at night" (1882), from moonlighter in reference to members of organized bands that carried on agrarian outrages in Ireland. And compare moonshine. Moonlighter in American English meant "one of a party who go about serenading on moonlit nights" (by 1897).
1705, "phase of the moon, particular recurrent appearance presented by the moon (or Mercury or Venus) at a particular time," back-formed as a singular from Modern Latin phases, plural of phasis, from Greek phasis "appearance" (of a star), "phase" (of the moon), from stem of phainein "to show, to make appear" (from PIE root *bha- (1) "to shine").
Latin singular phasis was used in English from 1660 for each of the aspects of the moon. General (non-lunar) sense of "aspect, appearance, stage of development at a particular time" is attested by 1841. Meaning "temporary difficult period" (especially in reference to adolescents) is attested from 1913.
"perigee of the moon, perihelion of a planet" (plural apsides), 1650s, from Latin apsis "arch, vault" (see apse).
1590s, "situated under the moon," hence "earthly, mundane" (old cosmology), from Modern Latin sublunaris, from sub "under, beneath" (see sub-) + lunaris (see lunar). It owes its special sense to the old cosmology of heavenly spheres and ultimately to Aristotle:
The treatise On the Heavens sets forth a pleasant and simple theory. Things below the moon are subject to generation and decay; from the moon upwards, everything is ungenerated and indestructible. [Bertrand Russell, "A History of Western Philosophy"]