ADJ

female, male
opposite
At that age they can started becoming shy with the opposite sex
single
a single-sex school
fair/fairer, gentle
(humorous) (= women; some women may find these terms annoying)

SEX + NOUN

change
She's had a sex change operation
equality
discrimination, inequality
ratio

PREP

between the ~es
differences/inequalities/relations between the sexes

PHRASES

the battle of the sexes
The quiz is a battle of the sexes between a team of male students and a team of female students
on grounds of sex
discrimination on grounds of sex
irrespective/regardless of sex
The word 'man' can refer to all humans, irrespective of sex

ADJ

anal, oral, penetrative, vaginal
gay, homosexual, lesbian
heterosexual
good, great, passionate
safe
unprotected, unsafe
consensual, non-consensual
extra-marital, illicit, premarital
kinky
casual, promiscuous
unlawful
He was convicted of having unlawful sex with an underage girl
explicit, gratuitous
Films containing explicit sex are banned

VERB + SEX

engage in, have
She had never had sex before
consent to
refuse
obtain, procure

SEX + NOUN

life
a healthy sex life
drive, urge
a low sex drive
appeal
Despite his age, he still has a lot of sex appeal
act, practices
photos showing sex acts safer sex practices
therapist, therapy
organ
hormone
education
abuse, assault, attack, crime, offence
child sex abuse
maniac
He had a reputation of being a sex maniac
fiend (informal), offender, pest
(informal)
film, scene, show
symbol
She wants to be known as a singer rather than as a sex symbol
shop
aid, toy
scandal

PREP

~ between
sex between consenting adults
~ with
sex with her husband