From Longman Dictionary of Contemporary Englishlife vestˈlife vest noun [countable] 
American EnglishTTW a life jacket
American EnglishTTW a life jacketExamples from the Corpus
life vest• She loaded the oars and gas can and life vest, then turned to close the boathouse doors.• The outboard was gone, too, and the gas can and the orange life vest and the two fiberglass oars.• Kathy pulled her arms inside the life vest.• Kathy tucked her chin into the life vest, closed her eyes.• Maybe she forgot to put on the life vest. 