/i fish"euhn see/ , n. , pl. efficiencies .
1. the state or quality of being efficient; competency in performance.
2. accomplishment of or ability to accomplish a job with a minimum expenditure of time and effort: The assembly line increased industry's efficiency.
3. the ratio of the work done or energy developed by a machine, engine, etc., to the energy supplied to it, usually expressed as a percentage.
4. See efficiency apartment .
[ 1585-95; efficientia, equiv. to efficient- (see EFFICIENT) + -ia -Y 3 ]