sexual intercourse 
noun [mass noun]
Sexual contact between individuals involving penetration, especially the insertion of a man’s erect penis into a woman’s vagina, typically culminating in orgasm and the ejaculation of semen.There is growing evidence of tolerance of sexual activity other than heterosexual sexual intercourse....
- He also decried any sex education that talked about homosexuality or even sexual intercourse.
- She was guilty of committing adultery by having sexual intercourse.