| Acronym | Definition |
|---|
| ISIM | IMS (IP Multimedia Subsystem) Subscriber Identity Module |
| ISIM | International Institute for the Study of Islam in the Modern World |
| ISIM | Institute for the Study of International Migration |
| ISIM | Integrated Science Instrument Module (James Webb Space Telescope) |
| ISIM | International Society for Improvised Music (Ann Arbor, MI) |
| ISIM | International Society of Internal Medicine (founded in 1948) |
| ISIM | International Symposium on Induced Mutations in Plants (International Atomic Energy Agency) |
| ISIM | Interlinking Statistical Information |