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

The three-year war erupted at the onset of the collapse of Yugoslavia, with Bosnia and Herzegovina becoming one of the first countries to declare its independence from the country in 1992. — Idaho Statesman, 2 July 2026

Symptoms include sudden onset of vomiting, diarrhea and stomach pain that can last three days, according to the CDC. — ABC News, 2 July 2026

The abnormal heat has been driven by the onset of El Niño, a natural climate pattern characterized by unusually warm waters along the equatorial tropical Pacific Ocean. — Laura Paddison, CNN Money, 1 July 2026

The onset is gradual enough to mask how serious it’s become, and family members often start compensating long before the person recognizes there’s a problem. — Allison Palmer, Miami Herald, 1 July 2026

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
• binet
• 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