1620s, from French accolade "an embrace, a kiss" (16c.), from Provençal acolada or Italian accollata, ultimately from noun use of a fem. past participle of Vulgar Latin *accollare "to embrace around the neck," from Latin ad "to" (see ad-) + collum "neck" (see collar (n.)), from PIE root *kwel- (1) "revolve, move round."
The original sense is of an embrace about the neck then the tapping of a sword on the shoulders to confer knighthood. Extended meaning "praise, award" is by 1851. Also see -ade. The earlier form of the word in English was accoll (mid-14c.), from Old French acolee "an embrace, kiss, especially that given to a new-made knight," a noun use of the past participle of the verb acoler. The French noun in the 16c. was altered to accolade, with the foreign suffix, and English followed suit.