an unjustified failure to perform substantially the obligations arising from promises in a contract
A significant mistake, omission or failure to follow an agreement. The United States argues that Iraq is in material breach of United Nations resolutions for making false statements about the presence of banned weapons or failing to disclose that it possessed banned weapons.
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 (rescission, damages, specific performance) from the contravening party.
A breach of a contract that gives the injured party the right to cancel the remainder of the contract and to sue for damages resulting from the breach.
a breach (violation, failure to perform) which is important, substantial, not trivial.
the kind of breach which goes to the very essence of the contract and thus allows the parties to rescind