2
: beginning, commencement
the onset of winter
the onset of age-related diseases
Synonyms of onset
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
Pigsqueak With the onset of cold temperatures, the green foliage of pigsqueak (Bergenia cordifolia) turns brilliant shades of maroon.
—
Megan Hughes, Better Homes & Gardens, 28 Dec. 2025
The onset of the year could bring a major turning point, an ending or victory in relation to your ambitions and professional life.
—Kyle Thomas, PEOPLE, 28 Dec. 2025
At least 49 buildings have collapsed due to the weather since the onset of Winter, the GMO added.
—Caitlin Danaher, CNN Money, 28 Dec. 2025
Fasten loose objects or shelter objects in a safe location prior to the onset of winds.
—Ca Weather Bot, Sacbee.com, 27 Dec. 2025
See All Example Sentences for onset
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Megan Hughes, Better Homes & Gardens, 28 Dec. 2025
The onset of the year could bring a major turning point, an ending or victory in relation to your ambitions and professional life.
—Kyle Thomas, PEOPLE, 28 Dec. 2025
At least 49 buildings have collapsed due to the weather since the onset of Winter, the GMO added.
—Caitlin Danaher, CNN Money, 28 Dec. 2025
Fasten loose objects or shelter objects in a safe location prior to the onset of winds.
—Ca Weather Bot, Sacbee.com, 27 Dec. 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 1 Jan. 2026.
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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