oh

oh 1530s, interjection expressing various emotions, a common Indo-European word (Cf. O.Fr. ô, oh; L. o, oh; Gk. o; O.C.S., Lith. o; Goth., Du., Ger. o; O.Ir. a; Skt. a), but not found in Old English, which translated L. oh with la or eala.

Often extended for emphasis, e.g. Oh, baby, stock saying from c.1918; oh, boy (1910); oh, yeah (1924). Reduplicated form oh-oh as an expression of alarm or dismay is attested from 1944. Oh-so "so very" (often sarcastic or ironic) is from 1922. Oh yeah? "really? Is that so?" attested from 1930.