c.1300, but this now is regarded as a Pennsylvania German dialect formation. Meaning "in a past time" (but not necessarily just one time) is from c.1250. Once upon a time as the beginning of a story is recorded from 1595. Slang once-over "inspection" is from 1915. At once originally (c.1230) meant "simultaneously," later "in one company" (c.1300), and preserved the sense of "one" in the word; the phrase typically appeared as one word, atones; the modern meaning "immediately" is attested from 1531.
allO.E. eall "all, every, entire," from P.Gmc. *alnaz (cf. O.Fris., O.H.G. al, O.N. allr, Goth. alls), with no certain connection outside Gmc. All-fired (1837) is U.S. slang euphemism for hell-fired. First record of all out "to one's full powers" is 1880. All-star (adj.) is from 1889; all-American is from
1888, with ref. to baseball teams composed of the best players from the U.S. All-terrain vehicle first recorded 1970. All clear as a signal of "no danger" is recorded from 1902. All right, indicative of approval, is attested from 1953.