A mistake refers to an erroneous belief or understanding regarding a fact or law that affects the parties involved in a legal proceeding. In the context of relief from judgment, a mistake can be grounds for a party to seek to overturn or modify a judgment if it is shown that the mistake significantly impacted the outcome of the case. This term highlights the importance of accurate information and understanding in legal processes, as well as the potential for courts to rectify errors that have led to unjust results.