GTSI
| Acronym | Definition |
|---|---|
| GTSI | Government Technology Services Inc. |
| GTSI | Government Technology Services, Inc. (Chantilly, VA) |
| GTSI | Greyhound Travel Services, Inc. (former subsidiary of Greyhound Lines) |
| GTSI | Group TETRA (Terrestrial Trunked Radio) Subscriber Identity (telecommunications) |