Invalidate
Pronunciation : In*val"i*date
Part of Speech : v.
Etymology : [From Invalid null.]
Definition : Defn: 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.
t. [imp. & p. p. Invalidated; p. pr. & vb. n. Invalidating.]
Source : Webster's Unabridged Dictionary, 1913