on·​set | \ ˈȯn-ˌset How to pronounce onset (audio) , 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

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 There’s no official consensus anyway on how to define the condition, which has more than 200 potential symptoms and can vary in onset from immediately after the infection resolves to months later. Erin Prater, Fortune, 6 Aug. 2022 These many and varied possibilities surrounding the onset and contributing factors make fibromyalgia difficult to diagnose. Bryant Stamford, The Courier-Journal, 4 Aug. 2022 Since new pharmaceutical treatments may be years from being available for patients, some Alzheimer’s researchers are looking more to early detection and prevention such as exercise to slow the onset or progression of the disease. Berkeley Lovelace Jr., NBC News, 2 Aug. 2022 This pain or tenderness may continue until the start of your period and then linger for a few days after its onset, according to Johns Hopkins Medicine. Rozalynn S. Frazier, SELF, 29 July 2022 And in eastern Kentucky, a rapid onset of rainfall caused catastrophic flash flooding and record river heights. Judson Jones, CNN, 29 July 2022 There are a few options for tree owners trying to blunt the beetle’s onset. Morgan Krakow, Anchorage Daily News, 25 July 2022 With the onset of the pandemic and the closures that followed in March 2020, Agonafer, like countless others, was forced to turn to takeout. Los Angeles Times, 22 July 2022 To add insult to injury, Death Valley as a surface-level alien conspiracy in the Eisenhauer era is far less interesting from its onset and deeply unsatisfying, being riddled with inconsistencies at every turn. Allaire Nuss, EW.com, 20 July 2022 See More

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.

First Known Use of onset

circa 1522, in the meaning defined at sense 1

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Time Traveler for onset

Time Traveler

The first known use of onset was circa 1522

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Dictionary Entries Near onset

on second thoughts



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Last Updated

12 Aug 2022

Cite this Entry

“Onset.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/onset. Accessed 18 Aug. 2022.

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More Definitions for onset


on·​set | \ ˈȯn-ˌset How to pronounce onset (audio) , ˈän- \

Kids Definition of onset

1 : beginning sense 1 the onset of winter


on·​set | \ ˈȯn-ˌset, ˈän- How to pronounce onset (audio) \

Medical Definition of onset

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

More from Merriam-Webster on onset

Nglish: Translation of onset for Spanish Speakers

Britannica English: Translation of onset for Arabic Speakers


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