ef·fi·cien·cy 
/ɪˈfɪʃənsi/ noun
plural ef·fi·cien·cies /ɪˈfɪʃənsi/ noun 1 : the ability to do something or produce something without wasting materials, time, or energy : the quality or degree of being efficient [noncount] ▪ Because of her efficiency, we got all the work done in a few hours. ▪ The factory was operating at peak efficiency. ▪ a car with greater fuel efficiency [=a car that uses fuel more efficiently] ▪ A furnace with 80 percent fuel efficiency wastes 20 percent of its fuel. [plural] (technical) ▪ The company is trying to lower costs and improve efficiencies. 2 [count] US : efficiency apartment
