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

Manufacturing innovation has historically followed a familiar arc: point solutions to fix discrete issues, application-level changes to improve efficiency, and system-level breakthroughs such as the assembly line. —Forbes.com, 13 Aug. 2025

But another College Football Playoff appearance hinges on quarterback Maddux Madsen’s efficiency as the focal point of the offense in the post-Ashton Jeanty era. —Jon Wilner, Mercury News, 13 Aug. 2025

Yet consensus is lacking on how to balance AI’s efficiencies with maintaining students’ critical thinking skills, leaving schools at a crossroads where increased reliance on AI now could entrench it deeply in future education. —Sharon Goldman, Fortune, 12 Aug. 2025

Ford aims to compete with Chinese automakers through ingenuity and efficiency, not by lowering labor costs. —Jamie L. Lareau, Freep.com, 12 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