onset

noun

on·​set ˈȯn-ˌset 

ˈän-

1

: attack, assault

withstand the onset of the army

2

: beginning, commencement

the onset of winter

the onset of age-related diseases

Synonyms of onset

• attack
• assault
• onslaught
• raid
• offensive
• aggression
• offense
• strike

Examples of onset in a Sentence

the walls withstood the onset of the first battalion

the claim that if you take enough vitamin C at the onset of a cold, you'll often recover faster

Recent Examples on the Web

This sentiment is deeply ingrained and persists despite the continent’s urgent need to raise funds to rearm, replenish stocks, and modernize its defense industrial base since the onset of Russia’s war in Ukraine. —Douglas Rediker, Foreign Affairs, 17 Dec. 2025

The dashboard said 28 cases involved people who were unvaccinated or had unknown vaccination status, meaning there was no evidence of receipt of a measles-containing vaccine or MMR vaccine 0-13 days prior to measles exposure or symptom onset. —Christina Hall, Freep.com, 16 Dec. 2025

Director Ron Howard and Grazer, who were also part of the Vulture interview, recalled Carrey struggling onset because of his Grinch costume. —Nino Paoli, Fortune, 15 Dec. 2025

Because there is often a long latency period between exposure and symptom onset, diagnoses are frequently delayed, according to DPH. —Bonny Chu, FOXNews.com, 11 Dec. 2025

Word History

First Known Use

circa 1522, in the meaning defined at sense 1

Phrases Containing onset

• adult-onset diabetes
• juvenile-onset diabetes

Rhymes for onset

• abet
• asset
• baguette
• banquette
• barbette
• beget
• beset
• brevet
• briquette
• brunet
• brunette
• burette

Kids Definition

onset

noun

on·​set ˈȯn-ˌset 

ˈän-

1

: attack entry 2 sense 1

2

: beginning sense 1

Medical Definition

onset

noun

on·​set ˈȯn-ˌset, ˈän- 

: the initial existence or symptoms of a disease

the onset of scarlet fever