'Wattmeter' definitions:

Definition of 'wattmeter'

(from WordNet)
noun
An instrument for measuring in watts the flow of power in an electrical circuit

Definition of 'Wattmeter'

From: GCIDE
  • Wattmeter \Watt"me`ter\, n. [Watt + meter.] (Physics) An instrument for measuring power in watts, -- much used in measuring the energy of an electric current. [1913 Webster]