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.
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