noun

onset

ON-seht

noun

The point at which something, especially an illness or a change, first begins.

"Doctors caught the disease at its onset, before symptoms appeared."

"The onset of winter brought the first frost of the year."

In phonetics, the consonant sound or sounds that come before the vowel in a syllable.

"In the word "cat," the onset is the /k/ sound."

How to Use Onset

Learner’s notes

In plain EnglishThe very beginning of something, especially when it develops or arrives — a disease, a season, a change.

Common pairings

sudden onset onset of symptoms onset of winter

onset past tense, onsets plural, onsets singular

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Doctors caught the disease at its _____, before symptoms appeared.

From on- + set, echoing the older Old English onsettan ("to press down upon, oppress").