| Acronym | Definition |
|---|
| PNI | Psychoneuroimmunology |
| PNI | Positivo, Negativo, Interesante (Spanish: Positive, Negative, Interesting) |
| PNI | Princeton Neuroscience Institute (Princeton University; Princeton, NJ) |
| PNI | Prescott New Instructions |
| PNI | Physical Network Inventory (various companies) |
| PNI | Producción Nacional Independiente (Venezuela) |
| PNI | Pacific Neuropsychiatric Institute (Seattle, Washington) |
| PNI | Perineural Invasion |
| PNI | Progressive Networks, Inc. |
| PNI | Pharmaceutical News Index |
| PNI | Palestinian National Initiative |
| PNI | Positive, Negative, Interesting (decision making) |
| PNI | Porter Novelli International (public relations; various locations) |
| PNI | Pohnpei, Caroline Islands, Micronesia - Pohnpei International (Airport Code) |
| PNI | Pacific Nanotechnology, Inc. (Santa Clara, CA) |
| PNI | Prescott New Instruction (Intel chips; early codename) |
| PNI | Partido Nacional Independiente (National Independent Party, Costa Rica) |
| PNI | Pro Natura International (Paris, France) |
| PNI | Paid/No Issue (banking term) |
| PNI | Productivity Network, Inc. |
| PNI | Paranormal Ideation |
| PNI | Pacific Neurosciences Institute |