Pir (disambiguation)
- Pir is the term for a pilgrimage site in Persian, frequently one of the Zoroastrian faith
- Pir, King of the Britons
- Pir is the Persian word for "old". When preceding a Persian name, the word indicates homage payed to the so titled, usually a sage or wise elder
- PIR is an acronym for the Protein Information Resource, a major protein information database and bioinformatics resource
- PIR is an acronym for Parrot Intermediate Representation, part of Parrot
- PIR is an acronym for Passive InfraRed sensors, and often used as part of a security system
- PIR is an initialism for the Phoenix International Raceway
- Parent(s) In Room, signifying to people in chat rooms or instant message conversations that someone's parents are in the room and to watch what is said.