| Acronym | Definition |
|---|
| PIR | Parents In Room (chat) |
| PIR | Post(-mortem) Incident Review |
| PIR | Passive Infrared |
| PIR | Protein Information Resource |
| PIR | Public Interest Registry |
| PIR | Phoenix International Raceway |
| PIR | Peak Information Rate (frame relay) |
| PIR | Parachute Infantry Regiment |
| PIR | Portland International Raceway (Portland, OR, USA) |
| PIR | Post Implementation Review |
| PIR | Polyisocyanurate |
| PIR | Property Irregularity Report (reporting lost/damaged luggage at an airport) |
| PIR | Public Infrastructure Renewal (Canada) |
| PIR | Private Information Retrieval (cryptography protocol/concept) |
| PIR | Project Implementation Report |
| PIR | Price Is Right (TV show) |
| PIR | Program Information Report |
| PIR | Protein Identification Resource |
| PIR | Partners in Injury Reduction (Alberta, Canada) |
| PIR | Project Implementation Review (systems development methodology) |
| PIR | Priority Intelligence Requirement |
| PIR | Protocol Independent Routing |
| PIR | Pass In Review (military) |
| PIR | Priority Information Requirements |
| PIR | Pierre, SD, USA - Pierre Municipal Airport (Airport Code) |
| PIR | Potential Impact Radius (natural gas pipeline) |
| PIR | Pocono International Raceway |
| PIR | Police Initial Recruitment Test (UK; also seen as PIRT) |
| PIR | Pittsburgh Industrial Railroad |
| PIR | Phillips Investment Resources |
| PIR | Probabilistic Information Retrieval |
| PIR | Planned Independent Requirement |
| PIR | Project Initiation Report (information management) |
| PIR | Photo Interpretation Report |
| PIR | Position in Range |
| PIR | Problem Identification Report |
| PIR | Public Interest Review |
| PIR | Philippine Independence Ribbon |
| PIR | Portable ILS Receiver |
| PIR | Periodic Intelligence Review |
| PIR | Purchase Information Record |
| PIR | Personnel Information Roster |
| PIR | Photon Irradiance Response |
| PIR | Pressure Ignition Rocket |
| PIR | Problem Investigation Report |
| PIR | Planned Inventory Retrieval |
| PIR | Permanent Impairment Rate (worker's compensation) |
| PIR | Proportional-Intensity-Reduction |
| PIR | Product Improvement Report |
| PIR | Procurement Information Reporting |
| PIR | Primary Intelligence Requirement |
| PIR | Perpetual Inventory Record |
| PIR | Provisional Integrated Rating |
| PIR | Preliminary Inspection Requirements |
| PIR | Planned Installation Report |
| PIR | Program Incident Report |
| PIR | Process Information Report |
| PIR | Problem Investigation Request |