A contravention of the terms of a contract by one of the parties that is so large that it changes the very nature of the agreement between the parties and allows the innocent party to treat the contract as being at an end and pursue legal remedies (recision, damages, specific performance) from the contravening party
a breach serious enough to destroy the value of the contract and to give a basis for an action for breach of contract
A violation of a contract of such nature or importance that the innocent party may rescind the contract as well as recover damages