Definition of jacket

• n. - A short upper garment, extending downward to the hips; a short coat without skirts.
• n. - An outer covering for anything, esp. a covering of some nonconducting material such as wood or felt, used to prevent radiation of heat, as from a steam boiler, cylinder, pipe, etc.
• n. - In ordnance, a strengthening band surrounding and reenforcing the tube in which the charge is fired.
• n. - A garment resembling a waistcoat lined with cork, to serve as a life preserver; -- called also cork jacket.
• v. t. - To put a jacket on; to furnish, as a boiler, with a jacket.
• v. t. - To thrash; to beat.