From Longman Dictionary of Contemporary Englishvacuum flaskˈvacuum ˌflask noun [countable] British English DFUa special container that keeps liquids hot or cold SYN thermos
Examples from the Corpus
vacuum flask• Keep the mixture in a vacuum flask for 6-8 hours.• Fairfax's steward has packed sandwiches for us and an ancient vacuum flask of tea.• What if we place Professor Summerlee upon the table, within the vacuum flask, in place of the cat? 