TCT is a three letter acronym that can mean:

Texas City Terminal Railway (AAR reporting marks TCT)

The TCT Magazine, A magazine covering the rapid prototyping industry

The Coroner's Toolkit computer forensic software

thrombin clotting time, a test used in blood coagulation.

Tri-State Christian Television, a 24-hour Christian cable television network broadcasting to 15 U.S. States and Canada. (Was formerly known as Total Christian Television)

tungsten carbide tipped, generally when describing blades and saws used for woodworking or more commonly metalworking.