| Abbreviation | Definition |
|---|---|
| IO | The Intensity Of .... |
| IOCF | Instantaneous Ordinary Coherence Function |
| IOPB | Institute of Physics Bhubaneswar |
| IOPD | Integrated Optical Path Difference |
| IOPP | Institute Of Particle Physics |
| IOPP | Institute of Physics Publishing |
| IOPS | Institute Of Physics in Scotland |
| IOR | Index Of Refraction |
| IOSO | Increase Oscillation and Sustain Oscillation |
| IOT | Inductive Output Tube |
| IP | Induced Potential |
| IP | Interaction Point |
| IP | internal pressure |
| IPAP | Institute of Pure and Applied Physics |
| IPASS | Illinois Physics And Secondary Schools |
| IPB | Institute of Physics Belgrade |
| IPC | Individual Particle Correlation |
| IPC | Integrated Proton Current |
| IPCP | Institute of Problems of Chemical Physics |
| IPhO | International Physics Olympiad |