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 are people in the government who have made their intentions very clear at the onset, and those intentions were emptying Gaza of its inhabitants, expelling them, and returning the Jewish settlements there.
—
Isaac Chotiner, New Yorker, 21 May 2025
This alteration might trigger the onset of migraine or worsen migraine attacks, as well as causing more severe or frequent migraines.
—Brigid Dwyer, Verywell Health, 19 May 2025
Rather, there’s a mutually healing trajectory to this strange, secretive summer of playing house, and Petzold observes its gradual onset in fine details of gesture, expression and domestic routine — and its lapses when people fall intermittently out of character.
—Guy Lodge, Variety, 17 May 2025
With the onset of the warmer season, one fruiting shrub that is often sought yet rarely achieved successfully in the Kansas City area may once again be finding its way onto the wish list of prospective gardeners.
—Anthony Reardon, Kansas City Star, 16 May 2025
See All Example Sentences for onset
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Isaac Chotiner, New Yorker, 21 May 2025
This alteration might trigger the onset of migraine or worsen migraine attacks, as well as causing more severe or frequent migraines.
—Brigid Dwyer, Verywell Health, 19 May 2025
Rather, there’s a mutually healing trajectory to this strange, secretive summer of playing house, and Petzold observes its gradual onset in fine details of gesture, expression and domestic routine — and its lapses when people fall intermittently out of character.
—Guy Lodge, Variety, 17 May 2025
With the onset of the warmer season, one fruiting shrub that is often sought yet rarely achieved successfully in the Kansas City area may once again be finding its way onto the wish list of prospective gardeners.
—Anthony Reardon, Kansas City Star, 16 May 2025
See All Example Sentences for onset
Cite this Entry
“Onset.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/onset. Accessed 5 Jun. 2025.
Copy CitationKids Definition
onset
noun
on·set
ˈȯn-ˌset 
ˈän-
Medical Definition
onset
noun
on·set
ˈȯn-ˌset, ˈän-
: the initial existence or symptoms of a disease
the onset of scarlet fever
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