An error committed in relation to some matter of fact affecting the rights of one of the parties to a contract.

Mistakes in making a contract are distinguished ordinarily into, first, mistakes as to the motive; secondly, mistakes as to the person, with whom the contract is made; thirdly, as to the subject matter of the contract; and, lastly, mistakes of fact and of law.In general, courts of equity will correct and rectify all mistakes in deeds and contracts founded on good consideration.