Source : Webster's Revised Unabridged Dictionary (1913)

Invalidation \In*val`i*da"tion\, n.
   The act of inavlidating, or the state of being invalidated.

         So many invalidations of their right.    --Burke.

Source : WordNet®

invalidation
     n : (law) a formal termination (of a relationship or a judicial
         proceeding etc) [syn: {annulment}]