The term 'Hat-Rack Part' refers to a PEG, which is a three-letter word. A hat-rack part is a small piece of hardware used to hang hats, coats, and other items on a wall. It typically consists of a metal or wooden PEG that is attached to the wall with screws. The PEG is then used to hang items from it. Hat-rack parts are commonly found in homes, offices, and other places where people need to hang items.