Definition of "Sex" :

noun: activities associated with sexual intercourse

"They had sex in the back seat."

noun: the properties that distinguish organisms on the basis of their reproductive roles

"She didn't want to know the sex of the foetus."

noun: all of the feelings resulting from the urge to gratify sexual impulses

"He wanted a better sex life."

noun: either of the two categories (male or female) into which most organisms are divided

"The war between the sexes."

verb: tell the sex (of young chickens)

verb: stimulate sexually