air jackets

Noun

air jacket (plural air jackets)

1. A lifejacket.
   • AIR-JACKET. A leathern garment furnished with inflated bladders, to buoy the wearer up in the water.1867, William Henry Smyth, The Sailor’s Word-Book, London: Blackie & Son, page 28
2. An inflatable vest worn to cushion falls.
   • […] our army all should wear a new uniform; all our horse infantry should wear air jackets, and all our foot cavalry should wear cork waistcoats; and then ye know why they’d be all over the sea before you could say Jack Robinson.1765, George Alexander Stevens, The Celebrated Lecture on Heads, London: R. Richards, Part 3, p. 16
3. An enclosed space containing nothing but air that surrounds something in order to provide insulation.
   • In the first Daimler gasoline engines a current of air was forced through an air jacket surrounding the cylinder by means of a rotary fan mounted on the crank shaft.1906 November 7, E. Favary, “Air Cooling Devices”, in The Horseless Age: The Automobile Trade Magazine, volume 18, number 19