Wordnet 3.0
NOUN (1)
1. 
 a putout of a base runner who is required to run; 
 the putout is accomplished by holding the ball while touching the base to which the runner must advance before the runner reaches that base; 
- Example: "the shortstop got the runner at second on a force"[syn: force out, force-out, force play, force]
WordNet (r) 3.0 (2006):
force-out
    n 1: a putout of a base runner who is required to run; the
         putout is accomplished by holding the ball while touching
         the base to which the runner must advance before the runner
         reaches that base; "the shortstop got the runner at second
         on a force" [syn: force out, force-out, force play,
         force]