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

This echoed Frederick Winslow Taylor’s idea of scientific management, which sought efficiency through control and standardization of the labor process. — Literary Hub, 4 Sep. 2026

The application illustrates how intelligent multi-agent systems may support operational efficiency while addressing regulatory and compliance requirements. — Lyssanoel Frater, USA Today, 3 Sep. 2026

Formally verified by the European Solar Test Installation (ESTI), this benchmark shows the technical progress in scaling up high-efficiency thin-film architectures beyond sub-centimeter laboratory devices. — Mrigakshi Dixit, Interesting Engineering, 3 Sep. 2026

Uber is the latest company to flatten management structures to speed up decision-making and improve efficiency. — Samantha Subin, CNBC, 2 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