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

Still, the bank wants headcount to stay flat and using AI to encourage efficiency. —Meg Short, Fortune, 7 June 2026

Meanwhile, the five-star analyst noted that the major debate surrounding Chevron centers on inventory depth and whether the company can sustain upstream volumes over the long term without sacrificing capital efficiencies. —Tipranks.com Staff, CNBC, 7 June 2026

The efficiency with which this information moved through the SHA ecosystem was almost unsettling. —Rachel Ingram, Robb Report, 7 June 2026

By shrinking the motor footprint, manufacturers can free up valuable chassis space, improve overall packaging efficiency, and potentially enhance vehicle performance and range through better system integration. —Bojan Stojkovski, Interesting Engineering, 7 June 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