The term ARM HOLDER can be summarized by two crossword solutions: SLEEVE (6 letters) and HOLSTER (7 letters). A SLEEVE is a garment that covers the arm, usually from the shoulder to the wrist. It is often part of a shirt or dress. A holster is a device used to hold a firearm, typically on a person's hip. It is usually made of leather or nylon and is designed to protect the gun and make it easier to carry.