onset

American  

[on-set, awn-] / ˈɒnˌsɛt, ˈɔn- /

noun

• onsets
  plural

1. a beginning or start.

   the onset of winter.

2. an assault or attack.

   an onset of the enemy.

3. Phonetics. the segment of a syllable preceding the nucleus, as the gr in great.

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onset British  

/ ˈɒnˌsɛt /

noun

1. an attack; assault

2. a start; beginning

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Other Word Forms

Noun Inflected Forms

• onsets
  plural

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Etymology

Origin of onset

1525–35; on + set, after the verb phrase set on

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Compare meaning

How does onset compare to similar and commonly confused words? Explore the most common comparisons:

• onset vs. outset

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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.

Example Sentences

See Examples For:

onset onsets

All three companies that quarter posted their highest profits since the onset of the Ukraine war.

From The Wall Street Journal ● Oct. 9, 2026

Consumers watched the prices of goods like bananas rise after the onset of reciprocal tariffs, Mahoney noted, and fall only slightly after those tariffs were rescinded.

From The Wall Street Journal ● Oct. 8, 2026

This meant that a succession of actors played Arnold over the years, until their voices changed with the onset of puberty.

From Los Angeles Times ● Oct. 7, 2026

And for the first time since the onset of the Iran conflict, credit spreads — the extra yield investors demand to own corporate debt instead of a comparable Treasury bond — are sending a warning.

From MarketWatch ● Oct. 1, 2026

Then the prince went from his horse, and knelt by the bier in honour of the king and his great onset; and he wept.

From "The Return of the King" by J.R.R. Tolkien

“Following each meal, my entire family experienced acute onsets with violent vomiting, watery diarrhea, and profound weakness.”

From Los Angeles Times ● Oct. 13, 2026

Research also revealed associations between Agent Orange exposures and later development of nervous system degenerative diseases, and significantly higher rates and earlier onsets of dementia.

From Science Daily ● Feb. 14, 2024

He and his colleagues analyzed 1952-2011 temperature data and found the four seasons no longer occur equally and had irregular onsets.

From Seattle Times ● Sep. 22, 2021

We used to call these “family words” when I was a kid: rat, bat, cat, mat, etc., all have the “-at” rime with different consonant onsets.

From Slate ● Nov. 29, 2018

This warfare continued for a number of years, the Indians being generally successful, and large numbers of soldiers falling before their savage onsets.

From Historic Tales, Vol. 1 (of 15) The Romance of Reality by Charles Morris

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Related Words

• commencement
• dawning
• onslaught
• outbreak
• outset

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