效率

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.

The manner of this divine efficiency being far above
us. --Hooker.

2. (Mech.) The ratio of useful work to energy expended.
--Rankine.

{efficiency of a heat engine}, the ratio of the work done by
an engine, to the work due to the heat supplied to it.