onset

noun

on·​set ˈȯn-ˌset How to pronounce onset (audio)
ˈän-
Synonyms of onset
1
: attack, assault
withstand the onset of the army
2
: beginning, commencement
the onset of winter
the onset of age-related diseases

Synonyms of onset

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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
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Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
At the onset of summer season the airport similarly saw a decline in its passenger forecast amid rising energy prices. — Dj Simmons, Charlotte Observer, 2 Sep. 2026 Within a year of its onset, the economic depression practically eradicated the need to mint any new coinage for months. — Andrew Paul, Popular Science, 2 Sep. 2026 At its onset, the school president had asked people to embrace those within their proximity. — Sam McDowell, Kansas City Star, 30 Aug. 2026 The average age for simultaneous child and elder care is now 34, not Gen X, with 80% experiencing a sudden onset. — Jasmine Browley, Forbes.com, 30 Aug. 2026 See All Example Sentences for onset

Word History

First Known Use

circa 1522, in the meaning defined at sense 1

Time Traveler
The first known use of onset was circa 1522

Phrases Containing onset

Rhymes for onset

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Browse Nearby Words

onsen
onset
onsetter
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Cite this Entry

“Onset.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/onset. Accessed 4 Sep. 2026.

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Kids Definition

Medical Definition

onset

noun
on·​set ˈȯn-ˌset, ˈän- How to pronounce onset (audio)
: the initial existence or symptoms of a disease
the onset of scarlet fever
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