1560s, loan-translation of Dutch vrijbuiter "plunderer, robber," from vrijbuiten "to rob, plunder," from vrijbuit "plunder," literally "free booty," from vrij "free" + buit "booty," from buiten "to exchange or plunder," from Middle Dutch buten, related to Middle Low German bute "exchange" (see booty). Cf. filibuster. The back-formed verb freeboot is recorded from 1590s.