on·set | \ˈȯn-ˌset, ˈän-\

Definition of onset 

1 : attack, assault withstand the onset of the army

2 : beginning, commencement the onset of winter the onset of age-related diseases

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Examples of onset in a Sentence

the walls withstood the onset of the first battalion the claim that if you take enough vitamin C at the onset of a cold, you'll often recover faster

Recent Examples on the Web

Since the onset of austerity, local and central government have driven ever-harder deals with their contractors. The Economist, "Britain’s outsourcing model, copied around the world, is in trouble," 28 June 2018 Evidence of the ways neural tissue is partially destroyed after a stroke or the onset of dementia has been around for decades. Susan Pinker, WSJ, "New Skills Build New Brain Architecture, Research Shows," 14 June 2018 Crimes sometime lack motive, and so does the onset of disease. Sarah Weinman, The Cut, "Did Drinking Give Me Breast Cancer? I Don’t Know.," 18 Apr. 2018 The increased carbon dioxide that humanity has been relentlessly pumping into the air since the onset of the Industrial Revolution is acidifying the oceans. Diana Gitig, Ars Technica, "Herring could actually benefit from ocean acidification," 25 Mar. 2018 The onset of deficits exceeding a trillion dollars a year in the midst of low unemployment has not prompted any regret, or even a hint of willingness to compromise on the party’s rigid opposition to higher taxes. Jonathan Chait, Daily Intelligencer, "Trump’s New Economic Adviser Lawrence Kudlow Has Been Wrong About Everything for Decades," 14 Mar. 2018 Spring is notoriously wet in Cleveland, and the onset of heavier rain is, on average, landing earlier in the year as well. Justin Madden, cleveland.com, "Parma police find missing 12-year-old boy with autism," 28 Feb. 2018 The onset of winter has long been prime indoor rat season, as rodents scurry to get out from the cold. Eugene Register-guard, OregonLive.com, "Eugene's surging rat population has exterminators busy," 8 Jan. 2018 The Pine Tree State is the latest to grapple with the risk of an unusual adult-onset allergy to red meat, CBS affiliate WGME-TV in Portland, Maine, reports. Thomas Leavy, CBS News, "Maine on the lookout for ticks that cause red-meat allergy," 25 June 2018

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

circa 1522, in the meaning defined at sense 1

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Statistics for onset

Last Updated

21 Oct 2018

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Time Traveler for onset

The first known use of onset was circa 1522

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More Definitions for onset



English Language Learners Definition of onset

: the beginning of something


on·set | \ˈȯn-ˌset, ˈän-\

Kids Definition of onset

1 : beginning sense 1 the onset of winter


on·set | \ˈȯn-ˌset, ˈän- \

Medical Definition of onset 

: the initial existence or symptoms of a disease the onset of scarlet fever

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Comments on onset

What made you want to look up onset? Please tell us where you read or heard it (including the quote, if possible).


to reject or criticize sharply

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