retail (v.) Look up retail at Dictionary.com
mid-14c. (implied in retailing), from Old French retaillier "to cut off, pare, clip, divide," from re- "back" (see re-) + taillier "to cut, trim" (see tailor (n.)).

Sense of "recount, tell over again" is first recorded 1590s. The noun meaning "sale in small quantities" is from early 15c., from Middle French retail "piece cut off, shred, scrap, paring." Related: Retailed; retailing.