sekss

Etymology
Via other European languages, ultimately borrowed from.

Noun

 * 1) sex, gender the two groups in which most living beings can be divided, according to their role in the reproductive process
 * 2)  sex sexual intercourse, sexual activity
 * 1)  sex sexual intercourse, sexual activity

Usage notes
The use of to mean "biological group" apparently is (or is becoming) dated;  is more often found in this sense.