Definition of Contract modification:
Written, unilateral (but within the scope of changes clause), or mutually agreed upon (bilateral), change. A contract modification may introduce or cancel specifications or terms of an existing contract, while leaving intact its overall purpose and effect. Unilateral modifications are issued usually through a change order (modification order), the bilateral ones through a supplemental agreement. Also called contract amendment or modification of a contract.
Meaning of Contract modification & Contract modification Definition