The term ARM SUPPORT can be summarized by the crossword solution SLING, which is a five-letter word. A SLING is a device used to support and immobilize an injured arm or shoulder. It is typically made of cloth or canvas and is worn around the neck and across the back, with the arm placed in a pocket in the middle. Slings are commonly used to treat fractures, sprains, and other injuries to the arm or shoulder.