In-vā′i-dāte, v. t.

v. t. [imp. & p. p. INVALIDATED; p. pr. & vb. n. INVALIDATING.] [It. invalidare, Sp. invalidar, Fr. invalider. See supra.] To render invalid; to weaken or lessen the force of; to destroy the strength or validity of; to render of no force or effect; to overthrow; as, to invalidate an agreement or argument.