TTA
- Leucine
- TTA – Racing Elite League
- Tan Tan Airport
- Teacher Training Agency
- Technical Theatre Awards
- Terran Trade Authority
- Tetradecylthioacetic acid
- The Tough Alliance
- Thenoyltrifluoroacetone
- Tibial tuberosity advancement
- Tiny Toon Adventures
- Toledo Technology Academy
- Tomorrowland Transit Authority PeopleMover
- Tramway Touristique de l'Aisne
- Transfusion-transmitted anaplasmosis
- Transport Ticketing Authority
- Transport triggered architecture
- Tri-State Transit Authority
- Triangle Transit Authority
- Twenty-foot equivalent unit
- Ṭa (Indic)