Coitus is a technical term for sexual intercourse, specifically vaginal sex that includes penetration and ejaculation. It is the physical union of male and female genitalia accompanied by rhythmic movements. Coitus is a vehicle for the expression of emotion and intimacy. The term may sound unusual because it is an old technical term for sex. The word coitus is often used in scientific or medical contexts, and it is not commonly used in everyday conversation. Synonyms for coitus include sexual intercourse, sex, coupling, and congress.