WordNet (r) 3.0 (2006):

mercury-in-glass thermometer
    n 1: thermometer consisting of mercury contained in a bulb at
         the bottom of a graduated sealed glass capillary tube
         marked in degrees Celsius or Fahrenheit; mercury expands
         with a rise in temperature causing a thin thread of mercury
         to rise in the tube [syn: mercury thermometer, mercury-
         in-glass thermometer]