| Abbreviation | Definition |
|---|---|
| IRST | Independent Research Study Track |
| IRSU | Interdisciplinary Research |
| IRT | Icing Research Tunnel |
| IRT | Identification, Referral, and Tracking |
| IRT | individual research training |
| IRT | Innovation Research and Training |
| IRTA | Institute for Research and Technical Assistance |
| IRTC | Integrated Research and Training Center |
| IRTC | Intuitive Research and Technology Corporation |
| IRTF | Internet Research Task Force |
| IRTI | Interdisciplinary Research Training Institute |
| IRTI | Islamic Research Training Institute |
| IRTT | Institute for Research and Technology Transfer |
| IRTU | Industrial Research and Technology Unit |
| IRU | Innovative Research |
| IRWE | Integrated Research on Water in the Environment |
| ISARA | International Spatial Accuracy Research Association |
| ISARS | International School of Advanced Research Study |
| ISARS | International Society for Academic Research on Shamanism |
| ISBR | Institute for Scientific and Biblical Research |