Efficiency

noun

1. The extent to which time is well used for the intended task.

   "The efficiency of the planning department is deplorable."

2. The quality of producing an effect or effects.
3. The extent to which a resource, such as electricity, is used for the intended purpose; the ratio of useful work to energy expended.

   "The efficiency of this loudspeaker is 40%."

4. A one-room apartment.

   "I have an efficiency available June through July."