| Abbreviation | Definition |
|---|---|
| IPRA | International Professional Rodeo Association |
| IPRT | India Poker Ranking Tournament Tour Series |
| IPS | Innings Per Start |
| IPSC | International Practical Shooting Confederation |
| IPSL | Iowa Premier Soccer League |
| IPV | Iowa Power Volleyball |
| IPVA | Iowa Power Volleyball Alliance |
| IQB | Indiana Quiz Bowl |
| IR | Injured Reserve |
| IRB | International Rugby Board |
| IRC | Internet Ralley Competition |
| IRC | Internet Running Club |
| IRFU | Irish Rugby Football Union |
| IRL | Indy Racing League |
| IRL | Insane Racing League |
| IRL | International Racing League |
| IROC | Interleague Racing Online Competition |
| IROC | International Race Of Champions |
| IRP | Inherited Runs Prevented |
| IRP | Initial Readiness Position |