A hacksaw is a small hand saw with a thin blade and many tiny, sharp teeth. People use it to cut metal — a pipe, a bolt, a metal rod — not wood. A wood saw has bigger teeth; those teeth slip on metal or get damaged. A hacksaw’s teeth and blade are made for that hard job. The blade usually sits in a frame you can tighten, and when it gets dull you put a new blade in, rather than throwing the whole tool away. You can also use hacksaw as a verb: to hacksaw something is to cut it with this tool. It is a workshop word. Builders, plumbers, and people fixing things at home all say it. Though actually, some people pick up any small saw and call it a hacksaw. Strictly, the name belongs to the metal-cutting one.