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

Indeed, emerging evidence suggests that early detection and aggressive treatment of psychiatric symptoms may improve long-term outcomes by delaying the onset of clinical neurodegeneration and mitigating the cumulative biological stress that accelerates brain aging. —Eric J. Nestler, STAT, 28 Apr. 2026

Now, three years after the initial onset of symptoms, Mollie uses a wheelchair and crutches daily and was forced to move in with their father. —Toria Sheffield, PEOPLE, 25 Apr. 2026

Symptoms include sudden onset of fever, headache and muscle pain with a spotty rash. —Arricca Elin Sansone, Southern Living, 25 Apr. 2026

The Strait of Hormuz effectively shut down in early March at the onset of the Iran war, triggering a major bottleneck in global energy and petrochemical flows. —Alexa Lomonaco, CNBC, 23 Apr. 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