A mamzer (ממזר) is a person born from certain forbidden relationships, or the descendant of such a person, in the Hebrew Bible and Jewish religious law. A mamzer is someone who is either born of adultery by a married Jewish woman and a Jewish man who is not her husband, or born of incest (as defined by the Bible), or someone who has a mamzer a... Found on http://en.wikipedia.org/wiki/Mamzer
Mam'zer noun [ Hebrew mámz...r .] A person born of relations between whom marriage was forbidden by the Mosaic law; a bastard. Deut. xxiii. 2 (Douay version). Found on http://www.encyclo.co.uk/webster/M/15