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onset

n.
US //ˈɑnˌsɛt// UK //ˈɒnsɛt// on·set
  1. 1 the start of something unpleasant (n.)
    B2 Upper Intermediate

    the beginning of something, usually something that is difficult or unwelcome.

    the beginning or commencement of an event or state, typically one that is unpleasant or problematic.

    Example

    The sudden onset of winter caught many people without warm coats.

    Example

    The rapid onset of the economic crisis forced the government to implement emergency measures within forty-eight hours.

    Usage

    Usually follows the pattern 'the onset of [noun]'.

  2. 2 medical symptoms (n.)
    C1 Advanced Technical Medicine

    the moment when the first signs of an illness appear.

    the initial phase of a disease or medical condition when symptoms first become apparent to the patient or clinician.

    Example

    Early onset of the disease can sometimes be managed with a better diet.

    Example

    Clinicians noted that the early onset of symptoms in younger patients often correlated with a more aggressive progression of the underlying infection.

    Usage

    Often used with adjectives like 'sudden', 'gradual', or 'early'.

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  1. 3 linguistics (n.)
    C2 Proficiency Technical Academic Science

    the first part of a syllable, before the main vowel sound.

    the initial consonant or consonant cluster of a syllable, preceding the nucleus.

    Example

    In the word 'stop', the letters 'st' form the onset.

    Example

    The researcher analyzed how children acquire complex onsets in languages that allow three or more consonants before the vowel nucleus.

    Usage

    Used specifically in phonology to describe syllable structure.

  2. 4 a military attack (n.)
    C2 Proficiency Archaic Literary

    a sudden and fierce attack by an army.

    a military assault or a sudden, violent attack.

    Example

    The soldiers prepared themselves for the enemy's fierce onset at dawn.

    Example

    The fortress walls eventually crumbled under the repeated onset of the heavy cavalry and the relentless bombardment of the siege engines.

    Teacher's tip

    This sense is rare in modern speech; learners will mostly encounter it in historical novels or older poetry.

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).

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