| Abbreviation | Definition |
|---|---|
| ISHI | International Spiritual Hypnotherapy Institute |
| ISHP | I Stock House Plans |
| ISI | Illinois Swimming, Incorporated |
| ISI | Image Space Inc |
| ISI | Indians Service India |
| ISI | Information Services International |
| ISI | Infortext Systems, Incorporated |
| ISI | Innovative Systems Inc |
| ISI | Innovative Systems, Inc. |
| ISI | Installer Supply International |
| ISI | Instructional Systems Inc |
| ISI | Interact Solutions, Inc. |
| ISI | International Sports Images |
| ISI | International Students Inc |
| ISI | International Students, Inc. |
| ISI | International Students, Incorporated |
| ISI | Internet Securities Inc |
| ISIS | International Spa Importing Specialists |
| ISL | Itchen Stationers Ltd |
| ISM | In-transit Service Manager |