| Acronym | Definition |
|---|
| LTSI➣Laboratoire Traitement du Signal et de l'Image (French: Signal and Image Processing Laboratory) |
| LTSI➣Logistics and Transportation Services, Inc. (Baltimore, MD) |
| LTSI➣Lighthouse Technology Solutions, Inc. (various locations) |
| LTSI➣Lern Transfer System Inventar (German: Learning Transfer System Inventory) |
| LTSI➣Local Telecom Systems, Inc. (Nevada) |
| LTSI➣Land Title Services of Illinois, Inc. |
| LTSI➣Long-Term Spontaneous Improvement (biology) |