body warmer
From Longman Dictionary of Contemporary Englishbody warmerˈbody ˌwarmer noun [countable] British English a piece of warm clothing without arms that you wear over a sweater or a shirt, especially when you are outside a fleece body warmerExamples from the Corpusbody warmer• He was joined immediately by a burly guy in a padded leather body warmer over a navy blue rugby shirt.