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

Thanks to a shin problem, this was Sesko’s first start since the win against Liverpool on May 3, but his efficiency is already underlining his importance. — Cerys Jones, New York Times, 11 Sep. 2026

Two McDonald’s trailers were dispatching Quarter-pounders and Chicken McNuggets with the same military efficiency shown at the restaurants. — Devin Friedman, Rolling Stone, 11 Sep. 2026

Shows promise in testing Tested under simulated conditions, these specialized cells proved exceptionally durable, retaining roughly 96 percent of their efficiency after 300 days of storage. — Mrigakshi Dixit, Interesting Engineering, 11 Sep. 2026

This minimizes stigma and administrative burden for families while also maximizing efficiency for administration. — Mona Hanna, The Conversation, 10 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