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

According to its text, the ROAD to Housing Act of 2025 aims to boost the country’s housing supply, improve affordability, help reduce homelessness, expand access to homeownership, increase oversight and efficiency of federal regulations and housing programs. —Ana Teresa Solá, CNBC, 1 Aug. 2025

The firm claims to have identified tens of thousands of crypto casinos worldwide, each exploiting the same regulatory loopholes with devastating efficiency. —Boaz Sobrado, Forbes.com, 1 Aug. 2025

Mayor Tyrone Garner and Unified Government department heads emphasized their efficiency in delivering assistance to affected residents. —Madeline King, Kansas City Star, 1 Aug. 2025

Boards violating the Open Meeting Act often invoke explanations of efficiency or convenience. —Kelly G. Richardson, Oc Register, 1 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