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Added 9 October 2026

onset

/ˈɒnˌsɛt/ noun

In Latin: accessus Wiktionary

noun Definition from WordNet 3.1, Princeton University. Pronunciation from Wiktionary, via Kaikki.org. More about onset at Wordnik → Where our words come from →

The beginning or early stages.
the onset of pneumonia
(military) an offensive against an enemy (using weapons).
the attack began at dawn

Origin

From on- + set. Compare Old English onsettan (“to impose; oppress, bear down”). For semantic parallels for the meaning to assault, compare cognate Russian насе́сть pf (naséstʹ), наседа́ть impf (nasedátʹ).

From Wiktionary, via Kaikki.org (CC BY-SA)

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