Mamgabey \Mam"ga*bey\, n. [So called by Buffon from Mangaby, in Madagascar, where he erroneously supposed them be native.] (Zo["o]l.) Any one of several African monkeys of the genus {Cercocebus}, as the sooty mangabey ({C. fuliginosus}), which is sooty black. [Also written {mangaby}.]