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 transit favors efficiency with boundaries. —Tarot.com, The Orlando Sentinel, 20 Apr. 2026

The 2026 model, which serves the full size SUV market well, is noted for its powerful i-FORCE MAX twin turbo V6 hybrid powertrain, attracting buyers who want power and efficiency in a large SUV package. —Tony Leopardo, Mercury News, 19 Apr. 2026

Instead, its focus is placed on cutting efficiency, everyday carry comfort, and long-term usability. —New Atlas, 19 Apr. 2026

The Lakers acquired Kennard for his shooting – on a roster that could use the extra efficiency off the bench come the playoffs. —Benjamin Royer, Oc Register, 19 Apr. 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