TCL
- People's Libraries Society
- TCL (GTPase)
- TCL (public transport)
- TCL Electronics
- TCL Technology
- THINK C
- Tcl (programming language)
- Texas Collegiate League
- The Common Link
- Theological College of Lanka
- Thermostatically controlled load
- Tibial collateral ligament
- Tiny Core Linux
- Trade Centre Limited
- Transaction Control Language
- Transform, clipping, and lighting
- Transnational College of Lex
- Trinity College London
- Tung Chung line
- Tuscaloosa National Airport
- Twin City Lines
- UEFA Champions League