(group theory) A mapping of a mathematical group to the permutations of an object that is compatible with the group operation.

(firearms, primarily of revolvers) Requiring only a trigger pull to both cock and fire.

(slang) To succeed at seducing another person into sexual activity.

Full of action; dramatic and exciting.

The hero of a work of fiction containing action, whose heroism typically includes participation in that action.

(set phrase) One who acts or reacts boldly, without hesitation, and often without forethought, especially in situations which are adventurous or dangerous.

An artist involved in action painting.

plural of action painter

(idiomatic) A portion of the monetary gains or other benefits produced by some venture or activity; a share of participation in a venture or activity.

(firearms, historical) An early form of breechloading firearm action, where the heavy breechblock tilted downwards across a bolt mounted in the rear of the breechblock, operated by a lever under the rifle.