Sex most commonly refers to:
- Biological sex, the trait of certain reproducing organisms producing either male or female gametes
- Sexual reproduction, reproduction that combines multiple gametes
- Human sexual activity, a broad range of reproductive or erotic human practices
- Human sexuality, the way people express themselves in terms of, or experience, the above activities
- Sexual intercourse, the activity of using reproductive organs penetratively
- Animal sexual behaviour, the reproductive or erotic activities of non-human animals
- Copulation (zoology), in which a male introduces sperm to a female's body
- Legal sex or legal gender, a legal status
Sex or sexual may also refer to:
