| Abbreviation | Definition |
|---|---|
| IWPA | International Weight Pull Association |
| IWS | Internet Wrestling Syndicate |
| IWS | Island Water Sports |
| IWT | International WorkingTest competition |
| IWZ | Internet Wrestling Zone |
| IYF | In Your Face |
| IYSC | Irish Youth Sailing Club |
| IYT | Integrative Yoga Therapy |
| J | Jack |
| J | Joker |
| JAAA | Jamaica Amateur Athletic Association's |
| JAAA | Jamaica Athletics Administrative Association |
| JADCO | Jamaica Anti-Doping Commission |
| JAFA | Japan Australian Football Association |
| JAFFA | Jogging And Fitness For All |
| JAGS | Jamie Aspinall Golf Society |
| JAGS | Just Another Gaming System |
| JAHI | Johns Arbitrary Hitting Index |
| JAHI | John's Arbitrary Hitting Index |
| JAS | Japanese Amateur Softball |