dilatometer

/ˌdaɪləˈtɑmɪtər/
noun
  1. An instrument used to measure changes in the volume or dimensions of a substance, especially as a result of temperature changes or chemical reactions.
    • Modern dilatometers can detect even tiny expansions in materials used for building bridges.
    • In the lab, the dilatometer recorded precise changes in the liquid's volume as the temperature rose.
    • The scientist used a dilatometer to measure how much the metal rod expanded when heated.