onset

onset — noun

1. the point when something starts, most often a disease, a difficulty, or another

1.nounC1
Definition

the point when something starts, most often a disease, a difficulty, or another unwelcome change.

Example

The sudden onset of fever worried the parents.

sudden onset of + symptom

With the onset of winter, buses reached the mountain village less often.

with the onset of + season

Common collocations
  • sudden onset
  • early onset
  • the onset of symptoms
  • the onset of winter
  • the onset of pain
Synonyms
  • start

    more everyday and works in many ordinary situations

  • beginning

    broader and less formal; not limited to unwelcome events

  • outbreak

    used for sudden spread, especially of disease, fire, or violence

Antonyms
  • end

    the point when something finishes

  • recovery

    opposite direction in medical contexts after illness begins

Grammar Patterns

the onset of + illness/problem/season

Usage Note

Common in formal writing with 'of', especially for illness, pain, bad weather, war, or other major changes. Distinguish from the everyday 'start' or 'beginning': 'onset' is less natural for ordinary happy events like parties or holidays.

Common Mistakes

The onset of the party was fun.
The start of the party was fun.
'onset' is mainly used for illness, trouble, weather, or other notable changes, not ordinary social events.

2. the opening consonant sound, or consonant group, before the vowel in a syllable.

2.nounC2
Definition

the opening consonant sound, or consonant group, before the vowel in a syllable.

Example

Pointing at 'play' on the board, Ms. Lin said the onset is /pl/.

onset in phonetics

The teacher wrote the onset and the rhyme in different colors.

Common collocations
  • syllable onset
  • complex onset
  • word-initial onset
Synonyms
  • initial consonant

    close in simple cases, but onset can include more than one consonant

  • syllable opening

    plain-English explanation rather than the standard technical label

Antonyms
  • coda

    the consonant sound after the vowel in a syllable

Grammar Patterns

the onset is + sound

complex onset

Usage Note

Used in phonetics and phonology when a syllable is divided into parts such as onset and rhyme. Distinguish from sense 1: this sense is a technical term about speech sounds, not about the beginning of an event or illness.

Common Mistakes

In "chair", the onset is just c.
In "chair", the onset is /tʃ/.
onset refers to the opening sound, not simply the first written letter.

onset — suffix

Synonym discussion

Sense: noun/1

'Onset' is more formal than 'start' or 'beginning' and is especially common when something difficult or noticeable begins, such as illness, pain, winter, or war. 'Start' is the most general everyday word and fits almost any situation. 'Beginning' is also broad, but it often focuses on the first stage of a process or story rather than a sudden change. 'Outbreak' is narrower: it is used for disease, fire, fighting, or violence spreading suddenly. 'Arrival' is different again because it emphasizes the point when a person, thing, or time reaches you. Compare: 'the onset of symptoms' sounds natural, but 'the start of symptoms' is more everyday. 'The arrival of winter' focuses on winter coming, while 'the onset of winter' suggests winter beginning to be felt.

onset ↗start ↗beginning ↗outbreak ↗arrival ↗

Etymology

Old EnglishMiddle EnglishEnglish

'Onset' first appeared in English with the sense of an attack or rush forward, built from the older verb phrase 'set on'. From the idea of something striking or coming upon you, especially trouble or illness, the noun later developed the modern meaning of the point when something begins.