| Abbreviation | Definition |
|---|---|
| ICWU | International Chemical Workers Union |
| ICWU | Iron Cross Waifu Union |
| IDCU | Iowa Division of Credit Unions |
| IDU | Independent Democratic Union |
| IDU | International Democrat Union |
| IDUC | Ijesha Descendants Union of California |
| IDYU | International Democratic Youth Union |
| IEAU | International Entertainment Adult Union |
| IEIU | Irish Engineering and Industrial Union |
| IFCU | Iberville Federal Credit Union |
| IFCU | Inland Federal Credit Union |
| IFCU | INTEGRIS Federal Credit Union's |
| IFCU | Internationalites Federal Credit Union |
| IFCU | Irondequoit Federal Credit Union |
| IFJ | International Federation of Journalists |
| IFTU | Indian Federation of Trade Unions |
| IFTU | International Federation of Trade Unions |
| IFTU | Iraqi Federation of Trade Unions |
| IGIU | International Green Industry Union |
| IGUA | International Guards Union of America |