| Abbreviation | Definition |
|---|---|
| IMPACT | Ironworker Management Progressive Action Cooperative Trust |
| IMPFA | Indian Mouth Foot Painting Artists |
| IMPFA | Indian Mouth & Foot Painting Artists |
| IMU | Indiana Memorial Union |
| IMU | Iowa Memorial Union |
| IMU | Irish Missionary Union |
| IMU | Israel Mathematical Union |
| INC | Indian National Congress |
| INCD | Inter-governmental Negotiating Committee Decertification |
| INCU | International Network of Consumer Unions |
| INDEF | Indian Engineers Federation |
| INTG | Intersindical Nacional de Traballadores Galegos |
| INTO | Irish National Teachers' Organisation |
| INTUC | Indian National Trade Union Congress |
| INTUC | IndianNational Trade Union Congress |
| IOCU | International Organisation of Consumer Unions |
| IOCU | International Organisation of Consumers Unions |
| IOCU | International Organization Consumers Unions |
| IOMAU | International Okinawan Martial Arts Union (Flower Mound, TX) |
| IOU | Intersection over Union |