| Abbreviation | Definition |
|---|---|
| IRRI | International Resources and Recycling Institute |
| IRSA | Institute of Remote Sensing Applications |
| IRSA | Institute Of Risk And Safety Analysis |
| IRSC | Institute for Regional Studies of the Californias |
| IRSD | Institute of Research Social Development |
| IRSE | Institute of Railway Signal Engineers |
| IRSE | Institution of Railway Signal Engineers |
| IRSI | International Rationality Summer Institute |
| IRSS | Institute for Research in Social Science |
| IRT | Institute for Recruitment of Teachers |
| IRTA | Institute for Research and Technical Assistance |
| IRTC | Institute of Robotics and Technical Cybernetics |
| IRTE | Institute for Road Traffic Education |
| IRTI | Interdisciplinary Research Training Institute |
| IRTI | International Reformed Theological Institute |
| IRTI | Islamic Research and Training Institute |
| IRTI | Islamic Research Training Institute |
| IRTT | Institute for Research and Technology Transfer |
| IRTT | Institute of Road and Transport Technology |
| IRW | Institute for Research on Women |