Wiktionary
sexual relation
n. (context idiomatic English) Behaviour of a sexual nature between one or more individuals.
WordNet
sexual relation
n. the act of sexual procreation between a man and a woman; the man's penis is inserted into the woman's vagina and excited until orgasm and ejaculation occur [syn: sexual intercourse, intercourse, sex act, copulation, coitus, coition, sexual congress, congress, relation, carnal knowledge]