| Abbreviation | Definition |
|---|---|
| IRI | Inter Reward Interval |
| IRIS | Integrated Regional Information System |
| IRIS | Integrated Representative Information System |
| IRIS | Internal Revenue Information Services |
| IRIS | Iraq Resource Information Site |
| IRMH | Immigrant , Refugee and Migrant Health |
| IRO | Independent Review Organization |
| IROP | ICE Retirement Option Plan |
| IRP | Intramural Research Program |
| IRR | Internal Rate of Return |
| IRT | Immigration Review Tribunal |
| IRV | Instant Runoff Voting |
| ISAF | International Security Assistance Force |
| ISAM | Information Security Awareness Month |
| ISC | International Standards Committee |
| ISC | Interstate Stream Commission |
| ISCO | International Standard Classification of Occupations |
| ISDP | Information Systems Designated Procurement |
| ISF | Internal Security Force |
| ISIN | International Securities Identification Number |