Waiver of a contract right is knowingly giving up a right.
The essence of a waiver is when a party intentionally relinquishes a known right. It is well settled that when there is a no oral modification clause, the doctrines of waiver, release and estoppel do not apply. (“ Waiver is an intentional relinquishment of a known right and should not be lightly presumed. ”) Gilbert Frank Corp. v. Fed. Ins. Co., 70 N.Y.2d 966, 968 ; Brooklyn Fed. Saving Bank v. 9096 Meserole St. Realty LLC, 29 Misc 3d 1220(A) [Kings Sup Ct 2010].