The term 'PART OF A JACKET' can be broken down into two crossword solutions: SLEEVE (6 letters) and LAPEL (5 letters). A SLEEVE is the part of a garment that covers the arm, from the shoulder to the wrist. It is usually sewn into the main body of the garment. A LAPEL is the part of a jacket or coat that folds over the chest and is typically fastened with a button. It is usually found on the left side of the garment and is used to add detail and style.