sexual_relation has definitions from the fields of biology,sexuality
[ noun ] (biology,sexuality) 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

Used in print

(Philip Reaves, "Who Rules the Marriage Bed?"...)

In one extreme case , cited by a Pittsburgh psychologist , an office worker 's wife refused to have sexual_relations with her husband unless he bought her the luxuries she demanded .