Legal Definition
A material breach is a significant or substantial violation of a contractual obligation, which substantially defeats the purpose of the contract. In legal contexts, it signifies a serious failure to perform a core term of an agreement, often justifying the termination of the contract.
Plain-English Translation
Imagine a promise in a contract. A 'material breach' means that one person broke a very important rule or promise. If the broken rule is big enough, it shows that the whole deal is seriously broken, and the other person decides to end the agreement because the damage is too great.