NUN could refer to:

• Saufley Field, airport, Pensacola, Florida, United States; IATA airport code NUN
• Nuneaton railway station, England; National Rail station code NUN

A nun is a member of a religious community of women, typically one living under vows of poverty, chastity, and obedience. She may have decided to dedicate her life to serving all other living beings, or she might be an ascetic who voluntarily chose to leave mainstream society and live her life in prayer and contemplation in a monastery or convent. The term "nun" is applicable to Catholics (eastern and western traditions), Orthodox Christians, Anglicans, Lutherans, Jains, Buddhists, Taoists, Hindus and some other religious traditions.