sex((chiefly with reference to people) sexual activity, including specifically sexual intercourse.
"they enjoyed talking about sex"google.comI. Havkin)
sex act(Finally, last December, guilty verdicts were handed down to a priest and nun who had gone to extraordinary lengths to protect their illicit relationship. The court found Sister Abhaya had walked in on them while they were engaging in a sex act in the kitchen, and killed her to conceal their sins.cnn.com4uzhoj)