. [ After Sir James Dewar, British physicist. ] A double-walled glass vessel for holding liquid air, liquid nitrogen, etc., having the space between the walls exhausted so as to prevent conduction of heat, and sometimes having the glass silvered to prevent absorption of radiant heat; -- called also, according to the particular shape,
Dewar bulb,
Dewar tube, etc. [ Webster 1913 Suppl. +PJC ]