| Abbreviation | Definition |
|---|---|
| IF | Intrinsic Field |
| IFD | Indentation Force Deflection |
| IFD | Internal Force Deflection |
| IFEL | Inverse Free Electron Laser |
| IFOV | Instantaneous Field Of View |
| IFR | Inertial Frame of Reference |
| IG | Infinitesimally Generating |
| IG | Inverse Gamma |
| IGL | Increased Grain Linearity |
| IGRA | interferon-gamma release assay |
| IGRF | International Geomagnetic Reference Field |
| IHT | Impact Hardness Tester |
| IIC | Impact Insurance Class |
| IIC | Ipact Insulation Class |
| IIP | International Institute of Physics |
| IJMP | International Journal of Materials Physics |
| IK | Inverse Kinematics |
| IL | Impact Line |
| ILD | Indentation Load Deflection |
| ILSS | Inter-Laminar Shear Strength |