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

Ratings for the State of the Union declined this year, so the boost in weekend viewing with the onset of the war likely contributed to the bumps for MS Now and CNN. —Rick Porter, HollywoodReporter, 12 Mar. 2026

Excessive air pollution Since the onset of US-Israeli strikes on February 28, at least four oil facilities near Tehran have been hit. —Mrigakshi Dixit, Interesting Engineering, 11 Mar. 2026

An example of this work from the Team Mutographs effort is a paper in the journal Nature on April 23 that looked for mutational signatures in early-onset colorectal cancer, which is increasing in many countries. —Paul Sisson, San Diego Union-Tribune, 9 Mar. 2026

These conditions echo the onset of the energy crises of the 1970s, which were triggered in large part by the Yom Kippur War and the Iranian Revolution of 1979. —Will Gottsegen, The Atlantic, 9 Mar. 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
• 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