From Longman Dictionary of Contemporary EnglishThermosTher‧mos /ˈθɜːməs $ ˈθɜːr-/ (also Thermos flask British English) noun [countable] trademark DFUa special container like a bottle, that keeps drinks hot or cold SYN flask British English
Examples from the Corpus
Thermos• I would also have managed to acquire a Thermos flask.• He was standing by his desk pouring a mug of coffee from a Thermos jug.• The glass tube shattering in a Thermos bottle?• I've put the Thermos of water in your pack - use it sparingly. 