Source : Webster's Revised Unabridged Dictionary (1913)

Evaporometer \E*vap`o*rom"e*ter\, n. [L. evaporare to evaporate
   + -meter: cf. F. ['e]vaporm[`e]tre.] (Physics)
   An instrument for ascertaining the quantity of a fluid
   evaporated in a given time; an atmometer.

Source : WordNet®

evaporometer
     n : an instrument that measures rate of evaporation of water
         [syn: {atmometer}]