1. A short upper garment, extending downward to the hips; a short coat
without skirts.
2. 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.
3. (Mil.) In ordnance, a strengthening band surrounding and reënforcing
the tube in which the charge is fired.
4. A garment resembling a waistcoat lined with cork, to serve as a life
preserver; -- called also cork jacket.
Blue jacket. (Naut.) See under Blue. -- Steam jacket, a space filled
with steam between an inner and an outer cylinder, or between a casing
and a receptacle, as a kettle. -- To dust one's jacket, to give one a
beating. [Colloq.]
Jack"et, v. t. 1. To put a jacket on; to furnish, as a boiler, with a
jacket.