sober adj.

mid-14c., sobre, "moderate in desires or actions, habitually temperate, restrained," especially "abstaining from strong drink," also "calm, quiet, not overcome by emotion," from Old French sobre "decent; sober" (12c.), from Latin sobrius "not drunk, temperate, moderate, sensible," from a variant of se- "without" (see se-) + ebrius "drunk," which is of unknown origin.

The meaning "free from the influence of intoxicating liquors; not drunk at the moment" is from late 14c.; also "appropriately solemn, serious, not giddy." As "plain or simple in color" by 1590s. Jocular sobersides "sedate, serious-minded person" is recorded from 1705.

late 14c., sobren, "comfort, console, reduce to a quiet condition" (transitive), from sober (adj.). The sense of "free from intoxication" is by 1706; the extended sense of "bring back to reality" is by 1838. The sense of "render grave or serious" is attested from 1726. Soberize (1706) also was used. The intransitive sense of "become sober" is from 1820 (often but not originally with up) . Related: Sobered; sobering.