1) An error which causes one party or both parties to enter into a contract without understanding the obligations or results. Such a mistake can entitle one party or both parties to a rescission (cancellation) of the contract. A mistaken understanding of the law (as distinguished from facts) by one party only is usually not a basis for rescission. 2) An error as to facts or law made by a judge. Such errors may be harmless (not meriting a reversal) or material (a reversible error).