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 .