Old English reafere "plundering forager," agent noun from reafian (see reave (v.)). Cf. Old Frisian ravere, Middle Dutch rover, Dutch roover, Old High German roubari, German Räuber.
Online Etymology Dictionary, © 2010 Douglas Harper
Examples from the Web for reaver
Am I to be shot at like a popinjay at a fair, by any reaver or outlaw that seeks a mark for his bow?Sir Nigel
Arthur Conan Doyle