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

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:

• onset vs. outset

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

Aircraft production, for instance, plunged at the onset of the pandemic in 2020, when airlines delayed or canceled aircraft orders.

From The Wall Street Journal ● Jul. 10, 2026

But the effort was set aside after the onset of COVID-19, which caused massive disruptions across the Los Angeles Unified School District, said Michael Trujillo, a political strategist for Gonez.

From Los Angeles Times ● Jul. 4, 2026

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 year, the onset was delayed by three days and the monsoon's advance slowed for around two weeks across parts of western India, delaying field preparation and planting in several agricultural regions.

From BBC ● Jul. 1, 2026

Jimmie’s sisters Pat and Margaret, and their families, lived right across the street, so from the onset our house was full of life.

From "Reaching for the Moon" by Katherine Johnson

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

Much should be forgiven to a class which was daily and hourly exposed to such danger, so sudden in its onsets, so secret and stealthy, so all-pervading.

From Roman Society from Nero to Marcus Aurelius by Dill, Samuel

Related Words

• commencement
• dawning
• onslaught
• outbreak
• outset