{ } n. [ L. efficientia. ] 1. The quality of being efficient or producing an effect or effects; efficient power; effectual agency. [ 1913 Webster ]
The manner of this divine efficiency being far above us. Hooker. [ 1913 Webster ]
2. (Mech.) The ratio of useful work to energy expended. Rankine. [ 1913 Webster ]
efficiency of a heat engine, the ratio of the work done by an engine, to the work due to the heat supplied to it. [ 1913 Webster ]