Definition of sex:
activities associated with sexual intercourse; "they had sex in the back seat"
either of the two categories (male or female) into which most organisms are divided; "the war between the sexes"
all of the feelings resulting from the urge to gratify sexual impulses; "he wanted a better sex life"; "the film contained no sex or violence"
the properties that distinguish organisms on the basis of their reproductive roles; "she didn't want to know the sex of the foetus"
stimulate sexually; "This movie usually arouses the male audience"
tell the sex (of young chickens)