de·​fi·​cient | \ di-ˈfi-shənt How to pronounce deficient (audio) \

Definition of deficient

 (Entry 1 of 2)

1 : lacking in some necessary quality or element deficient in judgment bones deficient in calcium
2 : not up to a normal standard or complement (see complement entry 1 sense 1b(1)) : defective deficient strength … rusted and aging pipes … abetted by deficient maintenance and sabotage.— Adam Nossiter



Definition of deficient (Entry 2 of 2)

: a person or thing that is deficient a mental deficient

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Other Words from deficient


deficiently adverb

Synonyms & Antonyms for deficient

Synonyms: Adjective

Antonyms: Adjective

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Examples of deficient in a Sentence

Adjective Several bridges in the city are structurally deficient. a diet deficient in calcium can lead to weak bones
Recent Examples on the Web: Adjective Cooper is highly deficient in Vitamin D, which contributed to slow bone recovery. Michael Gehlken, Dallas News, 17 Aug. 2021 Last season the Sun Devils were deficient defensively, finishing 332nd out of 340 teams in rebounding margin and failing to get a stop down the stretch in crucial games. Michelle Gardner, The Arizona Republic, 3 Aug. 2021 Although iron is found in a variety of foods, approximately 10 million Americans are iron deficient. Stefani Sassos, Ms, Rdn, Cso, Cdn, Nasm-cpt, Good Housekeeping, 14 July 2021 However, as half of the species are data deficient, the status of many remains unknown. Daniela De Lorenzo, Forbes, 7 May 2021 Her office has recently reviewed several police investigations into officers’ use of deadly force and concluded that many of the internal police reviews were deficient. Washington Post, 13 July 2021 Allowing a child to race dirt bikes might have been a sign of mentally deranged and deficient parents., 13 Aug. 2021 They were held in unsanitary and deficient quarters, anywhere from several weeks to several months before being deported or being allowed to enter the country. Kaila Yu, CNN, 18 May 2021 Last year 300 trees were planted in tree-deficient areas of Nestor and Otay, as well as part of City Heights. Greg Moran, San Diego Union-Tribune, 6 Aug. 2021 Recent Examples on the Web: Noun The best way to hide the deficient, though, is through a dominating offense which brings us back to Jackson and Roman. Mike Preston,, 5 June 2021 Some research is also starting to show that many severe COVID-19 patients are vitamin D deficient. Fedor Kossakovski, Science, 15 Dec. 2020 But rising home prices are bailing out large numbers of the equity deficient: their number is down by more than 1.2 million in the last 12 months. Kenneth R. Harney, miamiherald, 22 Aug. 2017

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'deficient.' 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 deficient


1581, in the meaning defined at sense 1


1906, in the meaning defined above

History and Etymology for deficient


borrowed from Latin dēficient-, dēficiens, present participle of dēficere "to leave without enough, let down, be lacking, run short, fail," from dē- de- + facere "to make, bring about, perform, do" — more at fact


derivative of deficient entry 1

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Time Traveler for deficient

Time Traveler

The first known use of deficient was in 1581

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Dictionary Entries Near deficient

deficiency disease


deficient number

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Statistics for deficient

Last Updated

16 Sep 2021

Cite this Entry

“Deficient.” Dictionary, Merriam-Webster, Accessed 26 Sep. 2021.

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More Definitions for deficient



English Language Learners Definition of deficient

: not having enough of something that is important or necessary
: not good enough : not as good as others


de·​fi·​cient | \ di-ˈfi-shənt How to pronounce deficient (audio) \

Kids Definition of deficient

: lacking something necessary for completeness or health Her diet is deficient in proteins.


de·​fi·​cient | \ di-ˈfish-ənt How to pronounce deficient (audio) \

Medical Definition of deficient

 (Entry 1 of 2)

1 : lacking in some necessary quality or element a deficient diet
2 : not up to a normal standard or complement deficient strength
3 : having, relating to, or characterized by a genetic deletion



Medical Definition of deficient (Entry 2 of 2)

: one that is deficient a mental deficient

More from Merriam-Webster on deficient

Nglish: Translation of deficient for Spanish Speakers

Britannica English: Translation of deficient for Arabic Speakers


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