Wordnet 3.0
ADJECTIVE (1)
1. 
 capable of contracting or being contracted; 
- Example: "the contractile wings of an insect"
The Collaborative International Dictionary of English v.0.48:
Contractile \Con*tract"ile\, a. [Cf. F. contractile.]
   tending to contract; having the power or property of
   contracting, or of shrinking into shorter or smaller
   dimensions; as, the contractile tissues.
   [1913 Webster]
         The heart's contractile force.           --H. Brooke.
   [1913 Webster]
         Each cilium seems to be composed of contractile
         substance.                               --Hixley.
   [1913 Webster]
   Contractile vacuole (Zool.), a pulsating cavity in the
      interior of a protozoan, supposed to be excretory in
      function. There may be one, two, or more.
      [1913 Webster]
WordNet (r) 3.0 (2006):
contractile
    adj 1: capable of contracting or being contracted; "the
           contractile wings of an insect"