TTSI
| Acronym | Definition |
|---|---|
| TTSI | Total Transcription Solutions, Inc. (est. 2001; Quezon City, Philippines) |
| TTSI | Trail Termination Source Identifier |
| TTSI | Toshiba Technical Services International (Japan) |
| TTSI | Text to Speech Interface |
| TTSI | Travelling to School Initiative (UK) |
| TTSI | Thyrotroph T4 Sensitivity Index (pituitary-thyroid diagnostics) |
| TTSI | Thorn Transit Systems International, Ltd. (UK) |
| TTSI | Tandem Telecommunication Systems Inc. |
| TTSI | Taxpayer Treatment Service Improvement |