The Collaborative International Dictionary
Air jacket
Air jacket \Air" jack`et\ A jacket having air-tight cells, or cavities which can be filled with air, to render persons buoyant in swimming.
Wiktionary
air jacket
n. A jacket with airtight cells, or cavities which can be filled with air, to make the wearer buoyant when swimming.
WordNet
air jacket
n. an inflatable life jacket [syn: Mae West]