Putative father

A putative father, with some variations in specific language, generally means a man whose legal relationship to a child has not been established but who is alleged to be or claims that he may be the biological father of a child who is born to a woman to whom he is not married at the time of the child's birth.

There is no standard definition for the word "father" in statutes across the United States. Five States (as of 2010, Arizona, Nebraska, New York, North Carolina, and Virginia) as well as the District of Columbia, American Samoa, and the U.S. Virgin Islands, provide no legal definition for the term at all. Many states, however, have definitions for various categories of unwed fathers, with the term "putative father" being defined by statute in 12 States (as of 2010, these being Arkansas, Florida, Indiana, Iowa, Maine, Montana, Nevada, Ohio, Oklahoma, South Dakota, West Virginia, and Wyoming).

...
Wikipedia