re·​tar·​da·​tion | \ˌrē-ˌtär-ˈdā-shən, ri-\

Definition of retardation 

1 : an act or instance of retarding

2 : the extent to which something is retarded

3 : a musical suspension specifically : one that resolves upward

4a : an abnormal slowness of thought or action especially : mental retardation

b : slowness in development or progress

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Synonyms & Antonyms for retardation


braking, deceleration, downshift, letup, slowdown


acceleration, hastening, quickening

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Examples of retardation in a Sentence

The child suffered severe mental retardation. The chemical induced a retardation of cell growth.

Recent Examples on the Web

The Vantage’s brake pedal has a nice firm weight but little travel, retardation being down to pressure rather than movement. Mike Duff, Car and Driver, "2019 Aston Martin Vantage: We Slide Behind the Wheel of a Prototype," 28 Feb. 2018 The policy of retardation of submarine technology ended right after the beginning of the Anglo-German naval race (marked by the German Naval Laws of 1898 and 1900)., "America needs a new 'dreadnought strategy'," 28 July 2017 At the end Austen had psychomotor retardation and could barely move. Rene Chun, Los Angeles Magazine, "Inside the Los Angeles Clinic That Uses Ketamine to Treat Depression," 19 June 2017 The autism spectrum refers to a broad range of symptoms, from the relatively mild social awkwardness of Asperger's syndrome to profound mental retardation, debilitating repetitive behaviors and an inability to communicate. Maggie Fox, NBC News, "Fevers During Pregnancy Raise Autism Risk, Study Shows," 13 June 2017 J.D.S. suffered from cerebral palsy, epilepsy and mental retardation. Gray Rohrer,, "Scott signs bill giving $1M to Orlando woman raped in group home," 2 June 2017 The survey found that the majority of respondents would elect to screen for diseases like mental retardation, blindness, cancer and heart disease, and a hefty minority (20%) would screen for a disease that would result in death by the age of 50. Daniel Macarthur, WIRED, "The market for designer babies," 1 Feb. 2009 The front wheels threaten to lock up under what feels like normal levels of retardation at low speeds. Mike Duff, Car and Driver, "2018 Morgan 4/4," 30 June 2017

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

15th century, in the meaning defined at sense 1

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The first known use of retardation was in the 15th century

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More Definitions for retardation


re·​tar·​da·​tion | \ˌrē-ˌtär-ˈdā-shən, ri- \

Medical Definition of retardation 

1 : an abnormal slowness of thought or action especially : mental retardation

2 : slowness in development or progress

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Comments on retardation

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noxious or harmful

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