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

Onishchenko told the state news agency TASS that the onset of cold weather would likely prevent transmission. — Tim Lister, CNN Money, 4 Oct. 2026

Piotr Swat | Lightrocket | Getty Images On Friday, BioMarin announced five-year data from a Phase 3 trial for the drugs Pombiliti and Opfolda to treat late-onset Pompe disease, or LOPD. — Anna Rodin, CNBC, 2 Oct. 2026

This story has been updated to clarify that measles is infectious for four days prior to and for four days after the onset of a rash. — Rachel Carlson, NPR, 30 Sep. 2026

That’s while the box office is enjoying its biggest year since the onset of COVID, fueled by the best summer season ever recorded. — Rebecca Rubin, Variety, 30 Sep. 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