efficiency

noun

ef·​fi·​cien·​cy i-ˈfi-shən-sē 

plural efficiencies

1

: the quality or degree of being efficient

2

a

: efficient operation

b(1)

: effective operation as measured by a comparison of production with cost (as in energy, time, and money)

(2)

: the ratio of the useful energy delivered by a dynamic system to the energy supplied to it

3

: efficiency apartment

Synonyms of efficiency

• efficacy
• effectiveness
• efficaciousness

Examples of efficiency in a Sentence

Because of her efficiency, we got all the work done in a few hours.

The factory was operating at peak efficiency.

A furnace with 80 percent fuel efficiency wastes 20 percent of its fuel.

The company is trying to lower costs and improve efficiencies.

Recent Examples on the Web

That means more scrutiny on gross margins, infrastructure efficiency, how costs scale relative to revenue, and your serviceable debt capacity. — Denada Ramnishta, Forbes.com, 14 Sep. 2026

As Zhan Junhao, founder of Fujian Huace Brand Positioning Consulting, told The China Times, Balabala’s advantage comes from years of full-age-band kidswear positioning and supply-chain efficiency. — Li Jun, Footwear News, 14 Sep. 2026

Elvis says that if a lunar city of a million people could recycle water with the same efficiency as the International Space Station, with its 98% recovery rate, that would give the city at least 100 years of water. — Matthew Glasser, ABC News, 14 Sep. 2026

Rice had a rush efficiency rate of 24 percent against Notre Dame and was at 16 percent entering the fourth quarter. — Pete Sampson, New York Times, 14 Sep. 2026

Word History

Etymology

borrowed from Latin efficientia, from efficient-, efficiens "producing or giving rise to something, immediate (of a cause), efficient" + -ia -y entry 2

First Known Use

1633, in the meaning defined at sense 1

Phrases Containing efficiency

• efficiency apartment
• efficiency expert
• hyper-efficiency

Rhymes for efficiency

• deficiency
• proficiency
• sufficiency
• immunodeficiency
• inefficiency
• insufficiency

Kids Definition

efficiency

noun

ef·​fi·​cien·​cy i-ˈfish-ən-sē 

plural efficiencies

1

: the quality or degree of being efficient

2

: efficient operation

3

: the ratio of the useful energy delivered by a machine to the energy supplied to it