Definition of "efficiency" []

• The quality or property of being efficient. (noun)
• The degree to which this quality is exercised: The program was implemented with great efficiency and speed. (noun)
• The ratio of the effective or useful output to the total input in any system. (noun)
• The ratio of the energy delivered by a machine to the energy supplied for its operation. (noun)
• An efficiency apartment. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "Mechanical efficiency cannot tell me whether the tons are worth the illnesses, because there is *no common metric of mechanical efficiency*."
• "The announcement marks an exciting leap forward in efficiency for electric vehicles and working closely with their powertrain partner, Zytek Automotive, a brand new, innovative, lightweight and fully integrated electric motor, control system and battery will be designed to ensure that maximum efficiency is achieved."
• "SunPower, probably the industry leader in efficiency, is about to release a model with 23 percent efficiency."