material breach

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun law a breach of contract sufficiently serious to destroy the contract
• noun a breach of a treaty which releases other parties from any obligation under it

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a breach serious enough to destroy the value of the contract and to give a basis for an action for breach of contract