Sober means not affected by alcohol — clear-headed. Stay sober, the sober driver, sober enough to drive.
In recovery, sober means not drinking at all, and sobriety is counted in days and years. Sober up means to become sober, and sobering describes something that makes you serious: a sobering thought, sobering figures. It also describes a plain, serious manner or plain colours: a sober suit, a sober assessment. Note that sober as a judgement — a sober view — means calm and realistic rather than merely not drunk.
1adjectivesoberNot affected by alcohol.
“He was the only sober person in the room by ten.”
2adjectiveseriousSerious and plain.
“It was a sober assessment and nobody wanted to hear it.”
Too few real examples of this word to estimate which sense is commonest.
sober is a state of clear-headedness.
Latin sobrius is se-, without, plus ebrius, drunk — the same ebrius inside inebriated. The word is built as a negative, which is why the state has no positive name of its own.
Proto-Indo-European
*h₁egʷʰ- — drink
Latin
sōbrius
Old French
sobre
Middle English
sober
English, today
sober
Built from
Middle English sober, from Old French sobre, from Latin sōbrius, from se- (“without”) + ebrius (“intoxicated”), from Proto-Indo-European h₁egʷʰ- (“drink”). In the sense "not drunk," displaced native undrunken, from Old English undruncen.
Etymology from Wiktionary, CC BY-SA