The term 'A JACKET OPEN' can be solved by four different crossword solutions: ETON (4 letters), UNSNAP (6 letters), UNZIP (5 letters), and ANORAK (6 letters). Eton is a type of formal jacket, usually made of wool or cotton, with a narrow waist and wide lapels. Unsnap refers to the action of undoing a snap fastener, which is a type of closure used on jackets and other garments. UNZIP is the action of opening a zipper, which is a type of closure commonly used on jackets and other garments. ANORAK is a type of jacket, usually made of waterproof material, with a hood and a zipper closure.