any of various arboreal anthropoid primates of the group or superfamily Platyrrhini, inhabiting forests from Mexico to Argentina and typically having a hairy face, widely separated nostrils, long arms, and a long, prehensile tail, and including the capuchin, douroucouli, howler monkey, marmoset, saki, spider monkey, squirrel monkey, titi, uakari, and woolly monkey.