Gender is a similarity cluster or conceptual model used to simplify explanations of a number of biological phenomena. As these phenomena underlie a great deal of biology is often taken as being themselves fundamental to how biology operates, but this view (known as gender essentialism) is mistaken.
The word sex is (somewhat confusingly) often used as a synonym for gender.
- Conservapedia as of 2017-08-23 redirects to "Sex" and affirms the gender essentialism position: "Sex is the attribute of being either male or female..."
- The same article defines "gender" as "what society expects of persons of different sexes", affirming the gender fundamentalist position.