TDI
- Outfront Media
- Sattal
- TDI (engine)
- Tabbed document interface
- Tangerine Dream Independent
- Technical Diving International
- Technical Group of Independents (1979–1984)
- Technical Group of Independents (1999–2001)
- Telecommunications for the Deaf, Inc.
- Texas Department of Insurance
- The Dartmouth Institute for Health Policy and Clinical Practice
- Time delay and integration
- Tissue Doppler imaging
- Tolerable daily intake
- Toluene diisocyanate
- Total Drama Island
- Total Drama Island (2023)
- Total dual integrality
- Transport Driver Interface