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

About six months ago, she was diagnosed with early-onset Alzheimer’s. — R. Eric Thomas, Washington Post, 24 June 2026

Set nearly two centuries before the events of Game of Thrones, the series chronicles the onset of the civil war that will shape the fate of the Targaryen dynasty. — Francesca Pellegrini, Vanity Fair, 22 June 2026

The cause of Parkinson's disease is unknown, but several factors seem to play a role, according to Mayo Clinic, including exposure to toxins, genetics, being male (as men are more likely to develop the disease than women) and age (the average age of onset is around 70). — Sara Moniuszko, USA Today, 22 June 2026

But the arrival of New York Times travel writer Arthur Lloyd (Bashir Salahuddin), who has the clout to make Tom’s aspirations for Widow’s Bay come true, coincides with the onset of a mysterious fog. — Jennifer Ouellette, ArsTechnica, 21 June 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