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.
“There is high confidence in the onset of El Niño, followed by further intensification in the months that follow,” Wilfran Moufouma-Okia, the organization’s chief of climate prediction, said in a statement.
From Los Angeles Times • May 14, 2026
The onset of late spring will make it harder for Ukraine to spot Russian troops in verdant foliage, Kofman cautioned, meaning infiltration is likely to remain an important element of Russia’s coming summer offensive.
From The Wall Street Journal • May 12, 2026
A post mortem examination found Lois died from a sudden and severe lack of oxygen to her vital organs, likely caused by breathing in her first stool, and the onset of bacterial infection.
From BBC • May 11, 2026
"This discovery fundamentally changes our previous understanding of the onset of spring in the forest," says the Würzburg researcher.
From Science Daily • May 5, 2026
Where farmers depended on rains to water their fields, the onset of the rainy season meant that each morning the farmers gazed towards the horizon, sniffing the wind and straining their eyes.
From "Sapiens: A Brief History of Humankind" by Yuval Noah Harari
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.
