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.
Plus, natural-gas prices surged in Europe and Asia but barely rose in the U.S., a price divergence that has saved U.S. consumers trillions since the onset of the shale revolution.
From The Wall Street Journal • May 16, 2026
Graph shows the change in temperature at a specific location over time used to determine the onset of El Niño.
From BBC • May 14, 2026
Caroline Semaille, director of Public Health France, also said it could not be ruled out that people transmit the virus "48 hours before the onset of symptoms".
From Barron's • May 13, 2026
The Dome closed in March 2020 with the onset of the COVID-19 pandemic and in April 2021 it was announced that the venue would not be reopening.
From Los Angeles Times • May 12, 2026
Then more than 1.5 million German troops stormed over the Polish border, sparking the onset of World War II.
From "Reaching for the Moon" by Katherine Johnson
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.
