1911 Encyclopædia Britannica/Mistake

MISTAKE (i.e. take amiss), a misconception or error in thought or action. In law, the word is often used in the sense of ignorance or error, as when it is said that mistake of law affords no excuse for crime. In the law of contract, mistake is of special importance, and may occur either in a matter of law or in a matter of fact. In general, a mistake of law cannot be alleged in avoidance of the consequences of contracts or acts, although there are exceptions in which relief may be given. Mistake of fact, however, may be ground for avoidance, provided the mistake was not due to negligence. (See further Contract.)