on·​set ˈȯn-ˌset How to pronounce onset (audio)
: attack, assault
withstand the onset of the army
: 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 Many office workers made the shift to remote work at the onset of the Covid-19 pandemic in 2020. Rocio Fabbro, Quartz, 3 Apr. 2024 The onset of the pandemic, however, prodded state and local government agencies to impose significant business shutdowns to help curb the spread of the deadly virus. George Avalos, The Mercury News, 1 Apr. 2024 The child care search tool was launched at the onset of COVID-19 and is currently utilized by about 8,800 families, according to Sara Redington, chief philanthropy officer for The Miles Foundation. Lina Ruiz, Fort Worth Star-Telegram, 1 Apr. 2024 The militant group has been launching attacks on ships transiting the Red Sea and the Gulf of Aden since the onset of the Israel-Hamas war last October, disrupting shipping in the region. Greg Norman, Fox News, 29 Mar. 2024 By all accounts, the coming year looks like more of the same albeit a bit more uneventful at the onset – which is good news. Greg Petro, Forbes, 28 Mar. 2024 One area medical provider, South Bay Urgent Care, has recently reported increases in gastrointestinal symptoms such as diarrhea this winter with the onset of heavy rains. Paul Sisson, San Diego Union-Tribune, 28 Mar. 2024 Share [Findings] Ostrich-shell beads indicating the onset of the Initial Upper Paleolithic were found to have reached Shuidonggou by 39000 bc, and strontium isotope levels revealed the social exchange of ostrich-shell beads during the Late Quaternary in the Karoo Supergroup. Rafil Kroll-Zaidi, Harper's Magazine, 27 Mar. 2024 Perhaps the biggest sign to look for is the sudden onset of symptoms, Bowling said, like a person suddenly losing the ability to talk during a phone call. USA TODAY, 18 Mar. 2024

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'onset.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

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

Dictionary Entries Near onset

Cite this Entry

“Onset.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/onset. Accessed 15 Apr. 2024.

Kids Definition


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

Medical Definition


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

More from Merriam-Webster on onset

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