n. A light jack: a garment having but slight value as a defense against weapons.n. A short coat or body-garment; any garment for the body coming not lower than the hips.n. A waistcoat or vest.n. Something designed to be fastened about or cover the body for some other purpose than that of clothing: as, a strait-jacket, or a swimming-jacket.n. Clothing or covering placed around a cylindrical or other vessel of any kind, as a pipe, a cannon, a steam-boiler, a smokestack where it passes through the deck, etc., to give greater power of resistance, to prevent escape of heat by radiation, etc.n. A folded paper or open envelop containing an official document, on which is indorsed an order or other direction respecting the disposition to be made of the document, memoranda respecting its contents, dates of reception and transmission, etc.n. A young seal: so called from the rough fur.To cover with or inclose in a jacket: as, to jacket a steam-cylinder, etc.; to jacket a document. See jacket, n., 5 and 6.To beat; thrash.n. The loose wrapper of paper which protects the binding of a book.n. The sheet of cardboard or thick paper which covers the impression surface of a printing-cylinder.n. The hide or other natural covering of various animals, as sheep, seals, fish, etc.n. The skin of a potato.