Cuckoo Woman

A woman who deceives her partner into believing that he is the father of her child, while the biological father is someone else. This term is derived from the behavior of the cuckoo bird, which lays its eggs in other birds' nests, tricking them into raising the cuckoo's offspring.

"After years of thinking he was the father, John discovered his wife was a Cuckoo Woman and the child was someone else's."