efficience ef*fi"cience ([e^]f*f[i^]sh"ens), efficiency ef*fi"cien*cy ([e^]f*f[i^]sh"en*s[y^]), 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]

The Collaborative International Dictionary of English. 2000.