Mistake

n.
  1. An apprehending wrongly; a misconception; a misunderstanding; a fault in opinion or judgment; an unintentional error of conduct.
  2. (Law) Misconception, error, which when non-negligent may be ground for rescinding a contract, or for refusing to perform it.
    3. No mistake ,
    surely; without fail; as, it will happen at the appointed time, and no mistake.