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

• 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

For the last fifty years, much of human progress in work and management has been about optimizing for speed and efficiency. —Tomas Chamorro-Premuzic, Forbes.com, 25 Aug. 2025

The verdict Windows PowerToys is like a free upgrade pack for people who want more control and efficiency out of Windows. —Ken Colburn, AZCentral.com, 25 Aug. 2025

Morgan Stanley released a note recently seeing huge efficiencies ahead for companies as a result of AI: $920 billion per year for the S&P 500. —Dave Smith, Fortune, 24 Aug. 2025

This change improves efficiency and allows more priority students to be served. —Chicago Tribune, 24 Aug. 2025

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