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

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 Rohn focuses his research on better understanding the APOE4 gene, which poses a risk factor for late-onset Alzheimer’s. Mark Rudin, idahostatesman, "At Boise State, Idaho’s only Alzheimer’s researchers labor to grasp a growing disease," 14 June 2018 Volunteer Teresa Mittons’ love of food came from cooking with her father after he was diagnosed with early onset Alzheimer’s disease. Hannah Steinkopf-frank, RedEye Chicago, "Chicago in action: Give back to the city with these three volunteer organizations," 14 June 2018 Dennis,* an instructor at a major spinning franchise who’s in his early 30s, became concerned about his hearing and went to an audiologist, who diagnosed him with early onset hearing loss. Julia Belluz, Vox, "How your cycling class could give you hearing loss," 31 May 2018 This recommendation will cover many of the people with early onset disease. Marie Mccullough, Philly.com, "American Cancer Society urges colon cancer screening starting at 45, not 50," 30 May 2018 As at all commencements, their joy commingled with early-onset nostalgia. Matthew Ormseth, courant.com, "Trinity College Class Speaker Urges Fellow Graduates To Challenge Themselves," 20 May 2018 Susan Miller’s introduction to caregiving came when her husband was diagnosed at 55 with early-onset Alzheimer’s. Lisa Deaderick, sandiegouniontribune.com, "Taking from her own experience to support other caregivers," 20 May 2018 Fox had been diagnosed with early-onset Parkinson's in 1991, at 29. Chris Ballard, SI.com, "Same Warrior, New Battle: Brian Grant Won't Back Down From Parkinson's Disease," 2 May 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

7 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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