The Five Sexes
In 1993, Anne Fausto-Sterling wrote an essay for The Sciences, titled "The Five Sexes". In this essay, she argues that the two-sex system is not adequate to show the full spectrum of human sexualities. Instead, she suggests a five-sex system: males, females, "herms" , "merms", and "ferms".
According to Anne Fausto-Sterling, "herms" are named after hermaphrodites, people who are born with both a testis and an ovary, "merms" are male pseudo-hermaphrodites who are born with testes and some aspect of female genitalia, and "ferms" are female pseudo-hermaphrodites who are born with ovaries combined with some aspect of male genitalia.