Stillson wrenches are a popular tool used in plumbing to tighten or loosen pipes and fittings. They go by a few other names as well, including pipe wrenches, plumbing wrenches, and adjustable wrenches. However, the most common synonym for Stillson wrenches is "Monkey Wrench." The term "monkey wrench" originated from an American slang term for disruption and confusion, as this tool can cause chaos in the wrong hands. Another synonym for Stillson wrenches is "Crescent Wrench," which is a brand name that has become almost synonymous with adjustable wrenches. Regardless of what you call them, Stillson wrenches are a crucial tool in any plumber's toolbox.