mona (?m??n?) n (Animals) a W African guenon monkey, Cercopithecus mona, with dark fur on the back and white or yellow underparts[C18: from Spanish or Portuguese: monkey]Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014