Noun
vacuum flask that holds liquid air or helium for scientific experiments
Source: WordNetAbout 1892, the idea occurred to him of using vacuum-jacketed vessels for the storage of liquid gases – the Dewar flask (otherwise known as a Thermos or vacuum flask ) – the invention for which he became most famous. Source: Internet
This bomb held a cryogenic Dewar flask containing room for as much as 160 kilograms of liquid deuterium. Source: Internet