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

• aggression
• assault
• attack
• attempt
• blitz
• blitzkrieg
• charge
• coup de main
• descent
• offense
• offence
• offensive
• onslaught
• raid
• rush
• 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

Beaver’s Pond Press experienced this firsthand during the onset of the COVID-19 pandemic. —Mars King, Twin Cities, 9 Feb. 2025

There is a very strict window of time in which this medicine can be given — three hours from the onset of symptoms, although there can be exceptions under specific circumstances. —Katia Hetter, CNN, 7 Feb. 2025

The recovery was mired in a mix of challenges, including widespread lack of sufficient insurance, the onset of the COVID pandemic, steep terrain, aging septic systems and sky-high construction costs. —Ethan Baron, The Mercury News, 6 Feb. 2025

The groundwater was by now heavily contaminated—a catastrophic consequence of the sewage plants’ failure, poor sanitation in the tent cities, and the onset of heavy rains. —Claudine Ebeid, The Atlantic, 6 Feb. 2025

Word History

First Known Use

circa 1522, in the meaning defined at sense 1

Phrases Containing onset

• adult-onset diabetes
• juvenile-onset diabetes

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