noun (n)

• a gymnast who performs rolls and somersaults and twists etc.(noun.person)

  source: wordnet30
• a glass with a flat bottom but no handle or stem; originally had a round bottom(noun.artifact)

  source: wordnet30
• a movable obstruction in a lock that must be adjusted to a given position (as by a key) before the bolt can be thrown(noun.artifact)

  source: wordnet30
• pigeon that executes backward somersaults in flight or on the ground(noun.animal)

  Synonym:
  roller, tumbler pigeon
  

  source: wordnet30
• One who tumbles; one who plays tricks by various motions of the body; an acrobat.(noun)

  source: webster1913