Monkey  —n. (pl. -eys) 1 any of various primates, including marmosets, baboons etc., esp. A small long-tailed kind. 2 mischievous person, esp. A child.  —v. (-eys, -eyed) 1 (often foll. By with) tamper or play mischievous tricks. 2 (foll. By around, about) fool around. [origin unknown]