A set screw is typically used without a nut that is screwed into a threaded hole drilled in two objects to secure it. Once the screw fits into the first object, the projected end of the set screw presses firmly against the second object, working similarly to a clamp. These are often headless and are threaded along their entire length so that it ... More @Wikipedia
Hover over any link to get a description of the article. Please note that search keywords are sometimes hidden within the full article and don't appear in the description or title.