A life jacket is the float worn to keep a person's head above water. Put on a life jacket.
The point is that it turns an unconscious person face up, which a buoyancy aid does not. A life jacket in a locker has saved nobody, which is the whole argument for wearing it.
1nounlife jacketThe float worn to keep a person's head above water.
“The life jacket inflated the moment it hit the water.”
life jacket is equipment.
Practised in Sea & Sailing, Emergency & Rescue