overboard
adv.
"over the side of a ship," Old English ofor bord, from over + bord "side of a ship" (see board, n.2). Figurative sense of "excessively, beyond one's means" (especially in phrase go overboard) first attested 1931 in Damon Runyon.
〔李〕[over-=across 越过；board n.船舷 ⇒“across the board 越过船舷的”→] ad. from ship or boat in to water 从船上落入水中