on ‧ set /ˈɒnset $ ˈɑːn-, ˈɒːn-/ BrE AmE noun
the onset of something the beginning of something, especially something bad:
the onset of winter
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COLLOCATIONS
■ adjectives
▪ sudden
Consult the doctor if there is a very sudden onset of fever.
▪ abrupt
the abrupt onset of the rainy season in India
(=happening very quickly and suddenly)
▪ rapid
Symptoms may include the rapid onset of nausea and vomiting.
▪ early/late onset (=happening earlier or later than commonly happens – used especially about serious illnesses)
The patient had a family history of early onset Alzheimer's disease.
■ verbs
▪ delay the onset of something
An active and healthy lifestyle can delay the onset of disease in later life.
▪ mark the onset of something
The tradition originates from an old Celtic feast marking the onset of winter.