WordWeb Online

1. A toy consisting of a spool that is reeled up and down on a string by motions of the hand
    
2. [N. Amer, informal] A stupid incompetent person
   - dimwit [informal], nitwit [informal], half-wit [informal], doofus [N. Amer, informal], numpty [UK, informal], nelly [informal], donkey [informal], nellie [informal], dingleberry [US, informal], noodle [informal], dufus [N. Amer, informal], simp [N. Amer, informal]
    
3. Something that fluctuates up and down or between extremes

Derived forms: yo-yos

Type of: plaything, simple [archaic], simpleton, toy

Encyclopedia: Yo-yo