onset
Americannoun
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a beginning or start.
the onset of winter.
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an assault or attack.
an onset of the enemy.
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Phonetics. the segment of a syllable preceding the nucleus, as the gr in great.
noun
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an attack; assault
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a start; beginning
Etymology
Origin of onset
Compare meaning
How does onset compare to similar and commonly confused words? Explore the most common comparisons:
Explanation
When something is at its onset, it's at the beginning, just getting started, and it's often something that's not so pleasant. The onset of hurricane season is probably not the best time to visit the beach. If you catch an infection right at the onset and treat it immediately, the infection may not last so long. You can also have an early onset of something, and that usually means something you'd rather not have at all, as with early-onset Alzheimer's, a disease that usually appears after age 65. If you begin showing signs of the disease at a younger age than usual, you're said to have early-onset Alzheimer's.
Vocabulary lists containing onset
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Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
The backwardation really began to form at the onset of the war in late February, continued to widen until April 2 and has since tightened a bit, according to Dow Jones Market Data.
From MarketWatch • Apr. 13, 2026
The stampede was said to have started near the entrance to the site and was exacerbated by the onset of heavy rain.
From BBC • Apr. 12, 2026
"The decline in spatial memory indicates a progressive onset of neurodegenerative disease that we can attribute to CSE loss," says first author Suwarna Chakraborty, a researcher in Paul's lab.
From Science Daily • Apr. 8, 2026
New Vogue Spa’s treatment was supremely relaxing from the onset — part Head Spa, part facial, part eye care.
From Los Angeles Times • Apr. 6, 2026
“Is there such a thing as sudden onset schizophrenia?”
From "Everything, Everything" by Nicola Yoon
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
