1600, "at leisure, not occupied," from un- (1) "not" + past participle of employ (v.). Meaning "temporarily out of work" is from 1660s. There seems not to have been a verb *unemploy, but disemploy was used (1610s). The noun meaning "unemployed persons collectively" is from 1782.
No man has hired us
With pocketed hands
And lowered faces
We stand about in open places
And shiver in unlit rooms ...
[T.S. Eliot, from "Choruses from the Rock"]
1660s, "existing or happening at the same time," from Late Latin synchronus "simultaneous," from Greek synkhronos "happening at the same time," from syn- "together" (see syn-) + khronos "time" (see chrono-). Meaning "recurring at the same successive instants of time" is attested from 1670s. Related: Synchronously.
late 14c., "worldly, secular;" also "terrestrial, earthly; temporary, lasting only for a time," from Old French temporal "earthly," and directly from Latin temporalis "of time, denoting time; but for a time, temporary," from tempus (genitive temporis) "time, season, moment, proper time or season," from Proto-Italic *tempos- "stretch, measure," which according to de Vaan is from PIE *temp-os "stretched," from root *ten- "to stretch," the notion being "stretch of time." Related: Temporally.