A more thorough explanation:

A psychological father is a type of psychological parent, which refers to a person who provides for a child's emotional and physical needs on a regular basis. The psychological father may or may not be the biological father of the child. This term is often used in legal cases to determine custody and visitation rights.

For example, if a man has been living with and caring for a child as if he were the child's father, even though he is not the biological father, he may be considered a psychological father. In a custody battle, he may argue that he has developed a strong bond with the child and should be granted visitation or custody rights.