Mamzer (Hebrew: ממזר‎) is a Hebrew halachic term referring to a category of person. In Jewish religious law a mamzer is a person born from certain forbidden relationships, or the descendant of such a person. Roughly speaking, due to the Jewish definition of marriage, a mamzer is someone who is either born of adultery by a married woman, or born of incest (as defined by the bible), or someone who has a mamzer as a parent. However, this is an oversimplification.