The Collaborative International Dictionary of English v.0.48:

invalidated \invalidated\ adj.
   deprived of legal force.

   Syn: nullified.
        [WordNet 1.5]

The Collaborative International Dictionary of English v.0.48:

Invalidate \In*val"i*date\, v. t. [imp. & p. p. Invalidated;
   p. pr. & vb. n. Invalidating.] [From Invalid null.]
   To render invalid; to weaken or lessen the force of; to
   destroy the authority of; to render of no force or effect; to
   overthrow; as, to invalidate an agreement or argument.
   [1913 Webster]

WordNet (r) 3.0 (2006):

invalidated
    adj 1: deprived of legal force [syn: invalidated, nullified]

Moby Thesaurus II by Grady Ward, 1.0:

31 Moby Thesaurus words for "invalidated":
   belied, confounded, confuted, crippled, deflated, denied, disabled,
   disarmed, discarded, discredited, dismissed, disproved, disputed,
   disqualified, exploded, exposed, hamstrung, hog-tied, impugned,
   incapacitated, negated, negatived, overthrown, overturned,
   paralyzed, prostrate, punctured, refuted, rejected, shown up,
   upset