Definitions for "Flak jacket"
a sleeveless green vest that is designed to stop flak, or shrapnel from entering the body rather than being bullet proof. Historically, 70 percent of injuries on the battlefield are due to shrapnel from artillery shells. Most Army recruits are surprised to learn that the filler to the flak jacket is ballistic nylon rather than kevlar, a bullet stopping material.
jacket worn by jockeys and exercise riders to protect the ribs, back and kidneys; it is mandatory at Texas racetracks.
a MILSPEC jacket used by troops in wartime conditions