tumbler in WordNet English dictionary

1. pigeon that executes backward somersaults in flight or on the ground
   roller  tumbler  tumbler pigeon 
   
2. a glass with a flat bottom but no handle or stem; originally had a round bottom
   tumbler 
   
3. a movable obstruction in a lock that must be adjusted to a given position (as by a key) before the bolt can be thrown
   tumbler 
   
4. a gymnast who performs rolls and somersaults and twists etc.
   tumbler