ef·​fi·​cien·​cy | \ i-ˈfi-shən-sē How to pronounce efficiency (audio) \
plural efficiencies

Definition of efficiency

1 : the quality or degree of being efficient
2a : 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

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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.
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Recent Examples on the Web That comes as the Trump administration has announced its proposal to scrap more stringent Obama-era standards in favor or a more modest increase in fuel efficiency standards, according to USA Today. Eric D. Lawrence, Detroit Free Press, "Should GM worry about its green reputation? Group says automaker shouldn't side with Trump," 16 Apr. 2020 As President Donald Trump continues to target regulations written during the Obama administration, the latest rules to meet the chopping block were fuel efficiency standards written in 2012. Mark Olalde, USA TODAY, "Climate Point: Whale fieldwork, climate talks, EPA enforcement all on halt," 3 Apr. 2020 California Attorney General Xavier Becerra told reporters Tuesday the state would consider suing the federal government over the fuel efficiency standards. Aarian Marshall, Wired, "Trump Eases the Way for More Gas Guzzlers," 1 Apr. 2020 Trump administration officials argued that lowering the fuel efficiency standards will save lives by reducing the cost of newer, safer vehicles so more people can buy them. Andrew J. Tobias, cleveland, "Ohio Health Director Amy Acton sees benefits to homemade masks: Capitol Letter," 1 Apr. 2020 Even as the White House has been consumed with responding to the coronavirus crisis, Trump administration officials have raced to complete a new rule, expected to be announced today, that would virtually undo Obama-era fuel efficiency standards. Jill Cowan, New York Times, "Here’s what to know about the new effort, the," 31 Mar. 2020 The Trump administration has been itching to roll back Obama-era fuel efficiency standards. Roberto Baldwin, Car and Driver, "Trump Expected to Roll Back Fuel-Efficiency Standards on March 31," 30 Mar. 2020 The Obama administration used the moment to curb the industry’s emissions, implementing strict new fuel efficiency standards. Michael J. Coren, Quartz, "Coronavirus may get America to pass its biggest climate bill yet," 25 Mar. 2020 Higher efficiency standards for air conditioners and sinking prices for renewable energy—in particular, solar—offer the best chance to fill the gap, says Cozzi. Katherine Dunn, Fortune, "The great African air conditioning boom is about to begin—and it could strain the planet," 19 Mar. 2020

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'efficiency.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of efficiency

1633, in the meaning defined at sense 1

History and Etymology for efficiency

borrowed from Latin efficientia, from efficient-, efficiens "producing or giving rise to something, immediate (of a cause), efficient" + -ia -y entry 2

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Time Traveler for efficiency

Time Traveler

The first known use of efficiency was in 1633

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Statistics for efficiency

Last Updated

22 May 2020

Cite this Entry

“Efficiency.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/efficiency. Accessed 27 May. 2020.

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More Definitions for efficiency


How to pronounce efficiency (audio)

English Language Learners Definition of efficiency

: the ability to do something or produce something without wasting materials, time, or energy : the quality or degree of being efficient


ef·​fi·​cien·​cy | \ i-ˈfi-shən-sē How to pronounce efficiency (audio) \
plural efficiencies

Kids Definition of efficiency

: the ability to do something or produce something without waste

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Comments on efficiency

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