Definition of dewar in English:



  • A double-walled flask of metal or silvered glass with a vacuum between the walls, used to hold liquids at well below ambient temperature.

    • ‘The freezing device was composed of the rotating copper or silver disks and the liquid nitrogen dewar.’
    • ‘Liquid helium will boil off constantly through a special porous plug in the dewar to maintain the science probe at its required temperature for up to 18 months.’
    • ‘However, only the sample dewar was filled with liquid nitrogen.’
    • ‘The detector would be placed in a dewar, in effect a huge Thermos bottle.’
    • ‘But in 1999 the project experienced major development problems when the large thermos bottle, called a dewar, which holds the supercold helium surrounding the instruments, did not cool down as quickly as expected.’


Late 19th century: named after Sir James Dewar(see Dewar, Sir James).