A reservation made on a statement or offer that it is not an admission or cannot otherwise be used against the issuing party in future dealings or litigation with any determinative legal effect.
A statement set onto a written document such as a letter, which qualifies the signatory as exempt from the content to the extent that it may be interpreted as containing admissions or other interpretations which could later be used against him or her; or as otherwise affecting any legal rights of the principal of, or the person signing.
John: "I really want to tell my boss to go fuck himself, but I'm afraid of the legal consequences."
Al: "Don't worry, as long as you mention that your statement is 'Without Prejudice', he cannot use your words against you."
A phrase used by douches when telling you something that they dont want you to later hold against them
Without prejudice, I admit I hit your car