| Acronym | Definition |
|---|
| ISST | IBM (International Business Machines Corporation) Software Services for Tivoli |
| ISST | Fraunhofer Institut für Software- und Systemtechnik |
| ISST | International Society of Schema Therapy |
| ISST | Institute of Social Studies Trust |
| ISST | Institut de Santé et de Securité Au Travail (Tunisia) |
| ISST | International Schools Sports Tournament |
| ISST | Indian Standard Strip (steel construction) |
| ISST | In-Service Support Team |
| ISST | Infrared Surveillance of Surface Targets |
| ISST | Indian Standard Long Legged Tee Bar (steel construction) |
| ISST | ICBM (Intercontinental Ballistic Missile) SHF (Super High Frequency) Satellite Terminal |