1570s, from Middle French accoster "move up to," from Italian accostare or directly from Late Latin accostare "come up to the side," from Latin ad- "to" (see ad-) + costa "rib, side" (see coast (n.)). The original notion is of fleets of warships attacking an enemy's coast. Related: Accosted; accosting.[accost etymology, accost origin, 英语词源]