The Collaborative International Dictionary of English v.0.48:

Falsifiable \Fal"si*fi`a*ble\, a. [Cf. OF. falsifiable.]
   1. Capable of being falsified, counterfeited, or corrupted.
      --Johnson.
      [1913 Webster]

   2. able to be proven false, and therefore testable; as, most
      religious beliefs are not falsifiable, and are therefor
      outside the scope of experimental science.
      [PJC]

WordNet (r) 3.0 (2006):

falsifiable
    adj 1: capable of being tested (verified or falsified) by
           experiment or observation [syn: confirmable,
           verifiable, falsifiable]