| Programme For International Student Assessment | Academic & Science |
| Program For International Student Assessment | Academic & Science |
| Parents Increasing Student Achievement | Academic & Science |
| Parachute Industries Of Southern Africa | Business |
| Professional Investigators and Security Association | Business |
| Polygenic Inheritance Signal In Association | Community |
| Portable Instruction Set Architecture | Computer Hardware |
| Photovoltaic Information Strategy To Architects | Electronics |
| Programme for International Student Achievement | General |
| Protein Interfaces Surfaces and Assemblies | General |
| Preliminary Initial Site Assessment | General |
| Programme for International Assessment As | General |
| Program of International Student Assessment | General |
| Programmable Intelligent Services Accelerator | General |
| Proteins Interfaces Structures and Assemblies | General |
| Pair Interaction Structureless Approximation | General |
| Proximal Isovelocity Surface Area | General |
| Provisional Industrial Security Approval | General |
| Phoenix International Sport Automobiles | Governmental |
| Printer Seaman Apprentice | Governmental |
| Pacific Islander Student Alliance | Governmental |
| Plan for International Student Assessment | International |
| Partnerships for International Strategies in Asia | International |
| Photovoltaic Information System for Architects | Physics Related |
| Position Intensity and Shape Analysis | Physics Related |
| Phenix Integrated Simulation Application | Softwares |
| Pleasure Island Soccer Association | Sports |
| Pittsburgh Indoor Sports Arena | Sports |
| Pittsburgh Indoor Sports | Sports |
