A nun is a member of a religious community of women.
Nun, Nuns or NUN may also refer to:
- Nun (band), an Australian music group
- Nun (biblical figure)
- Nun (letter), in many Semitic alphabets
- Nun languages, a group of Eastern Grassfields languages
- Nun Mountain, a summit in Alaska
- Nun pigeon
- Nun River, Nigeria
- Nun, another term for the Egyptian god Nu
- Nun, a mountain of the Nun Kun massif in Kashmir, India
- Nun, the fish Oxynoemacheilus galilaeus
- NUN, IATA code for Saufley Field airport, Pensacola, Florida, U.S.
- NUN, National Rail station code for Nuneaton railway station, UK
- Nun, a Latin abbreviation for the nundinae market days