thermos flask



  • A double-walled vessel made from silvered glass or stainless steel in which the space between the inner and outer wall is a vacuum, mounted in a protective case and fitted with a closure. The vacuum reduces transfer of heat by convection and the silvering reduces transfer by radiation, thus the contents may be kept hot or cold for a considerable period of time (heat is eventually transferred by conduction). Other types of insulation, e.g. foamed polystyrene or polyurethane, are used for the same purpose especially in larger rectangular containers.


  • noun
    (written as Thermos flask)
    a trademark for a vacuum flask