| Partners In Research | Academic & Science |
| Pre-Insertion Resistor | Academic & Science |
| Prime Interest Rate | Accounts and Finance |
| Pierre (sd) | Airport Code |
| Prescribed Investor Rate | Business |
| Pier 1 Imports, Inc. | Business |
| Pile Installation Recorder | Business |
| Pupil Instruction Related | Community |
| Processor Information Rom (read-only Memory) | Computer Hardware |
| Protocol Independent Routing | Computing |
| Processor Identification Register | Computing |
| Priority Information Report | Computing |
| Plymouth International Raceway | General |
| Product Information Request (Release) | General |
| Production Illustration Request | General |
| Program Information Report | General |
| Public Interest Registry | General |
| Post Industrial Recycled | General |
| Peak Information Rate | General |
| Periodic Inspection Report | General |
| Parrot Intermediate Representation | General |
| Parachute Infantry Regiment | General |
| Prepare Interact Reflect | General |
| Property Irregularity Report | General |
| Private Information Retrieval | General |
| Pastor in Residence | General |
| Property Interest Report | General |
| Payment Information Repository | General |
| Polyisocyanurate And Is Rigid | General |
| Patient Information Reconciliation | General |
| Principal in Residence | General |
| Police Initial Recruitment | Governmental |
| Project Implementation Review | Governmental |
| Pieuse Innovation De Registres | International |
| Principia Internet Radio | Internet |
| Professiional In Residence | Jobs |
| Periodic Interest Rate | Maths |
| Partners In Recovery | Medical |
| Protein Information Resource | Medical |
| Parents In Room | Messaging |
| Primary Image Record | Military and Defence |
| Para Infantry Regiment | Military and Defence |
| Post-implementation Review | Military and Defence |
| Priority Intelligence Requirement | Military and Defence |
| Passive Infra Red | Military and Defence |
| Pass In Review | Military and Defence |
| Problem Identification Report | Military and Defence |
| Priority Information Requirement | Military and Defence |
| Priority Intelligence Requirements | Military and Defence |
| Pittsburgh Industrial Railroad | Regional |
| Pierre, South Dakota USA | Regional |
| Pittsburgh Industrial Railroad Incorporated | Regional |
| Portland International Raceway | Sports |
| Phoenix International Raceway | Sports |
| Pilar Airport | Transport & Travel |
