A child born of a married woman's adultery is a "mamzer". The child of a single woman and a man she could lawfully have married is not a "mamzer". It is irrelevant if the man is married or not. If one of the parents is not Jewish the child is not a "mamzer". Any child born to a married woman, even if she is known to have been unfaithful, is presumed to be her husband's, unless she is so promiscuous that such a presumption becomes unsupportable, or if she enters a public relationship with another man.