A vacuum flask is a container which is used to keep hot drinks hot or cold drinks cold. It has two thin silvery glass walls with a vacuum between them.
[British]regional note: in AM, usually use Thermos, vacuum bottle
vacuum flask in British English
noun
an insulating flask that has double walls, usually of silvered glass, with an evacuated space between them. It is used for maintaining substances at high or low temperatures
Also called: Thermos, Dewar flask
Examples of 'vacuum flask' in a sentence
vacuum flask
Perfect for tools or a vacuum flask, and it handily fits across the handlebars of your bike.