Ef*fi"cience (?), Ef*fi"cien*cy (?), n. [L. efficientia.]
The quality of being efficient or producing an effect or effects; efficient power; effectual agency.
The manner of this divine efficiency being far above us.
The ratio of useful work to energy expended.
Efficiency of a heat engine, the ratio of the work done an engine, to the work due to the heat supplied to it.
© Webster 1913.