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Synonyms

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.


onset British  
/ ˈɒnˌsɛt /

noun

  1. an attack; assault

  2. a start; beginning

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Other Word Forms

Noun Inflected Forms

Etymology

Origin of onset

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

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.

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Vocabulary lists containing onset

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.

See Examples For:

The onset of a potentially powerful El Nino weather pattern could boost global heat in the oceans and atmosphere even further in 2026 and into next year, scientists say.

From Barron's Jul. 3, 2026

This was also the case in October 2007 and in early 2022, just before the onset of significant bear-market declines, Paulsen observes.

From MarketWatch Jun. 26, 2026

His parents say any medicine that could delay the onset could make a real difference to hundreds of other children each year.

From BBC Jun. 22, 2026

According to the report, both men fell ill after spending time outdoors, one playing golf at five courses in Alameda and Contra Costa counties within 14 days of the onset of his symptoms.

From Los Angeles Times Jun. 16, 2026

Then Théoden was aware of him, and would not wait for his onset, but crying to Snowmane he charged headlong to greet him.

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

It is more common in women than men and typically onsets in 40s, often taking a significant toll on their quality of life.

From Science Daily Nov. 20, 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

Analyses of the passive playback experiments were the same as above, but the onsets and offsets of the sound sweeps were used as anchor points instead of the presses and the releases of the joystick.

From Nature Mar. 28, 2017

The second, a "Lamentation," begins with a most sonorous downward harmony, with rushes up from the bass like the lessening onsets of a retreating tide.

From Contemporary American Composers Being a Study of the Music of This Country, Its Present Conditions and Its Future, with Critical Estimates and Biographies of the Principal Living Composers; and an Abundance of Portraits, Fac-simile Musical Autographs, and Compositions by Hughes, Rupert

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