The term USE A BLOWTORCH is related to the job of welding, which is a process of joining two or more pieces of metal together by melting them and using a filler material. The four-letter solution for this term is WELD. Welding is a common technique used in many industries, such as automotive, construction, and manufacturing. It is often done with a blowtorch, which is a device that produces a flame hot enough to melt metal.