From Longman Dictionary of Contemporary Englishwarmerwarm‧er /ˈwɔːmə $ ˈwɔːrmər/ noun [countable] something, especially a piece of equipment, that is used to make or keep things warm a plate warmer
Examples from the Corpus
warmer• He was joined immediately by a burly guy in a padded leather body warmer over a navy blue rugby shirt. 