The crossword solution for the term 'Tooth of a Sort' is COG, which is a three-letter word. A COG is a type of tooth-like gear used in machinery to transfer rotational force from one part to another. It is usually made of metal and has teeth along its edge that fit into the teeth of another gear. Cogs are used in a variety of machines, from clocks to cars, and are an important part of many mechanical systems.