onset

on·set
O1N1S1E1T1
UK/ˈɒnˌsɛt//ˈɔnˌsɛt//ˈɑnˌsɛt/

noun

The initial phase of a disease or condition, in which symptoms first become apparent.

“the onset of puberty”

CommonScrabble 5

Meanings

onset1

nounonset (plural onsets)

plural onsets

  1. countablemedicineThe initial phase of a disease or condition, in which symptoms first become apparent.

    the onset of schizophrenia

    3 more examples

    After four days, the man claimed to be hearing hushed, unintelligible voices in his head. Assuming it was an onset of psychosis, the scientists paid little attention to the man’s concerns.

    2009 November 23, “Gateway of the Mind”, in Creepypasta, archived from the original on 26 Nov 2009

    In mild cases of hypergonadism prior to puberty, the onset of physical and mood changes may not be abnormally early or significant enough to cause any psychological or long-term physical complications.

    2018 June 25, James Roland, “What is Hypergonadism?”, in Healthline, archived from the original on 25 Apr 2025

    Widely credited as an early pioneer of the modern railway, Shooter died peacefully of his own choosing in Switzerland on December 13, having bravely lived with the onset of motor neurone disease in the final years of his life.

    2022 December 28, Paul Stephen, “Network News: Adrian Shooter CBE: rail industry mourns "a great man"”, in RAIL, number 973, page 6
  2. human sciencesThe initial portion of a syllable, preceding the syllable nucleus.

    The only regular sources for Sardinian *θ are Lat. ci̯ and ti̯, which are absent from Latin onsets. This means that the substantial number of words starting in *θ, discussed in § 3 – 7, cannot regularly continue a Latin form.

    2025, Cid Swanenvleugel, The Pre-Roman Elements of the Sardinian Lexicon, page 390
  3. acousticsThe beginning of a musical note or other sound, in which the amplitude rises from zero to an initial peak.
  4. A setting about; a beginning.

    the onset of puberty

    2 more examples

    There is surely no greater wisdom than well to time the beginnings and onsets of things.

    1625, Francis [Bacon], “Of Delays”, in The Essayes […], 3rd edition, London: […] Iohn Haviland for Hanna Barret, →OCLC

    Floods in northern India, mostly in the small state of Uttarakhand, have wrought disaster on an enormous scale. The early, intense onset of the monsoon on June 14th swelled rivers, washing away roads, bridges, hotels and even whole villages. Rock-filled torrents smashed vehicles and homes, burying victims under rubble and sludge.

    2013 June 29, “High and wet”, in The Economist, volume 407, number 8842, page 28

    Synonyms: start, beginning, beginning, birth, font, fount, inauguration, commencement

  5. obsoleteAnything added, such as an ornament or as a useful appendage.

    And will with deeds requite thy gentleness: And, for an onset, Titus, to advance Thy name and honourable family, Lavinia will I make my empress.

    c. 1588–1593 (date written), William Shakespeare, “The Lamentable Tragedy of Titus Andronicus”, in Mr. William Shakespeares Comedies, Histories, & Tragedies […] (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, →OCLC, [Act I, scene i]
  6. archaicAn attack; an assault especially of an army.

    Who on that day the word of onset gave.

    1800, William Wordsworth, Six thousand Veterans
    2 more examples

    Heralds, from off our towers, we might behold From first to last, the onset and retire Of both your armies

    c. 1596 (date written), William Shakespeare, “The Life and Death of King Iohn”, in Mr. William Shakespeares Comedies, Histories, & Tragedies […] (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, →OCLC, [Act II, scene i]

    And Peter's tired army cheered, and the newcomers roared, and the enemy squealed and gibbered till the wood re-echoed with the din of that onset.

    1950, C. S. Lewis, The Lion, the Witch and the Wardrobe

    Synonyms: storming

verbonset (third-person singular simple present onsets, present participle onsetting, simple past and past participle onset)

present singular third person onsets · participle present onsetting

  1. obsoleteTo assault; to set upon.
  2. obsoleteTo set about; to begin.

Onset2

Synonyms & antonyms

nounAn attack; an assault especially of an army.

Similar

More synonyms by meaning

nounthe beginning or early stages

Similar
Broader

noun(military) an offensive against an enemy (using weapons)

Broader
operationmilitary operation

Synonym sets from Open English WordNet, CC BY 4.0.

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).

Full word history & related roots →

Translations

Bulgarian начална фаза, атака
  • начална фаза (načalna faza)(medicine) initial phase of a disease or condition
  • атака (ataka)(archaic) attack, assault
  • нападение (napadenie)(archaic) attack, assault
Catalan atac
  • atac(phonology) initial portion of a syllable
Dutch aanvang, aanval
  • aanvang(medicine) initial phase of a disease or condition
  • aanval(archaic) attack, assault
Esperanto atako
  • atako(phonology) initial portion of a syllable
Finnish puhkeaminen, aluke
  • puhkeaminen(medicine) initial phase of a disease or condition
  • aluke(phonology) initial portion of a syllable
  • hyökkäys(archaic) attack, assault
  • aluke(acoustics) beginning of a musical note
  • atakki(acoustics) beginning of a musical note
French début, apparition
  • début(medicine) initial phase of a disease or condition
  • apparition(medicine) initial phase of a disease or condition
  • attaque(phonology) initial portion of a syllable
  • déclenchementsetting about, beginning
  • débutsetting about, beginning
  • assaut(archaic) attack, assault
  • attaque(archaic) attack, assault
  • attaque(acoustics) beginning of a musical note
German Anzeichen, Silbenansatz
  • Anzeichen(medicine) initial phase of a disease or condition
  • Silbenansatz(phonology) initial portion of a syllable
  • Silbenanfang(phonology) initial portion of a syllable
  • Silbenanlaut(phonology) initial portion of a syllable
  • Angriff(archaic) attack, assault
  • Ansturm(archaic) attack, assault
  • Anstieg(acoustics) beginning of a musical note
  • Einschwingvorgang(acoustics) beginning of a musical note
  • Anstrich(acoustics) beginning of a musical note
Hungarian szótagkezdet, nyitány
  • szótagkezdet(phonology) initial portion of a syllable
  • nyitány(phonology) initial portion of a syllable
  • kezdet(phonology) initial portion of a syllable
Indonesian awitan
  • awitan(medicine) initial phase of a disease or condition
Italian attacco
  • attacco(phonology) initial portion of a syllable
Korean 음절초
  • 음절초 (eumjeolcho)(phonology) initial portion of a syllable
Latin accessus
  • accessus(medicine) initial phase of a disease or condition
Persian آغازه
  • آغازه (âġâze)(phonology) initial portion of a syllable
Portuguese anábase, ataque
  • anábase(medicine) initial phase of a disease or condition
  • ataque(phonology) initial portion of a syllable
  • investida(archaic) attack, assault
Romanian debut, asalt
  • debut(medicine) initial phase of a disease or condition
  • asalt(archaic) attack, assault
  • atac(archaic) attack, assault
Russian при́ступ, ата́ка
  • при́ступ (prístup)(phonology) initial portion of a syllable
  • ата́ка (atáka)(archaic) attack, assault
  • наступле́ние (nastuplénije)(archaic) attack, assault
  • на́тиск (nátisk)(archaic) attack, assault
Spanish principio, ataque silábico
  • principio(medicine) initial phase of a disease or condition
  • ataque silábico(phonology) initial portion of a syllable
  • inicio silábico(phonology) initial portion of a syllable
  • arremetida(archaic) attack, assault
Swedish ansats
  • ansats(phonology) initial portion of a syllable

Rhymes & wordplay

Anagrams

Cite this entry
APA

onset. (n.d.). In WatkinsX Dictionary. Retrieved November 3, 2026, from https://dictionary.watkinsx.com/word/onset

MLA

“onset.” WatkinsX Dictionary, https://dictionary.watkinsx.com/word/onset. Accessed November 3, 2026.

Chicago

WatkinsX Dictionary, s.v. “onset,” accessed November 3, 2026, https://dictionary.watkinsx.com/word/onset.

Source: onset on Wiktionary, CC BY-SA 4.0.