| Abbreviation | Definition |
|---|---|
| IHU | Irish homing union |
| IJU | Indian Journalists Union |
| IJU | Islamic Jihad Union |
| IJU | The Journalists Union |
| IKKU | International Karate Kobudo Union |
| IKKU | Irish Kenpo Karate Union |
| IKU | International Karate Union |
| IKU | International Kennel Union |
| ILCA | International Labor Communication Association |
| ILGWU | International Ladies Garment Worker Union |
| ILGWU | International Ladies Garment Workers Union |
| ILGWU | International Ladies' Garment Workers' Union |
| ILGWU | International Ladies' Garment Workers' Union's |
| ILO | International Labor Organization |
| ILU | Interational Leprosy Union |
| ILU | International Labour Union |
| ILU | International Leonberger Union |
| ILWU | International Longshore and Warehouse Union |
| ILWU | International Longshoremen and Warehouse Union |
| IMCU | Indiana Members Credit Union |