O.E., reduced by assimilation of -t- from earlier O.E. betst "best, first, in the best manner," originally superlative of bot "remedy, reparation," the root word now only surviving in to boot (see boot (2)), though its comparative, better, and
superlative, best, transferred to good (and in some cases well). From P.Gmc. root *bat-, with comp. *batizon and superl. *batistaz. The verb "to get the better of" is from 1863. Best-seller is from 1889; best friend was in Chaucer (late 14c.). Best girl is first attested 1887 in a Texas context; best man is 1814, originally Scottish, replacing groomsman.