In this work, a single transistor-based threshold switch for a bio-inspired reconfigurable threshold logic is demonstrated with a metal-oxide-semiconductor field-effect transistor. A threshold logic can mimic biological neurons of brain by use of Boolean entities with threshold units. Various linear Boolean logic functions of AND, OR, NOT, NAND, and NOR are implemented without analog circuits such as a comparator for threshold operation. As a result, reconfigurable threshold logic is realized with a 6F(2) footprint. In addition to linearly separable logic functions, a linearly inseparable XOR logic function is also implemented using the same threshold switch. Edge detection, which is one of the most important functions for image recognition, is also demonstrated using the XOR logic function with the aid of semi-empirical circuit simulation by reflecting experimental data.