Longman Dictionary of Contemporary English - jacket

~ n 1 a short, light coat  (a denim jacket | Gene has to wear a jacket and tie to work.)  (- see also dinner jacket, life jacket) 2 a stiff piece of folded paper that fits over the cover of a book to protect it; dust jacket 3 AmE a stiff paper cover that protects a record; sleeve (4) BrE 4 a cover that surrounds and protects some types of machines