illness

illness — noun

1. a particular medical problem that affects a part of your body or your mind, ofte

1.nounA2
Definition

a particular medical problem that affects a part of your body or your mind, often with clear signs that a doctor can name

Example

Ezra caught a rare illness while working on a farm in Africa.

catch + [illness]: common verb collocation

Rin's illness got better after she took medicine for two weeks.

get better: common phrasal verb with illness

Common collocations
  • catch an illness
  • develop an illness
  • treat an illness
  • recover from an illness
  • rare illness
  • serious illness
  • mental illness
  • chronic illness
Synonyms
  • disease

    more technical/medical; focuses on the biological condition rather than the experience of being unwell

  • condition

    broader; can refer to any long-term health problem, not necessarily an active disease

  • disorder

    more formal, often used for mental health or for problems with specific body systems

  • sickness

    more informal; in British English often means temporary nausea or vomiting

Antonyms
  • health

    the state of being well, free from disease

Grammar Patterns

a/an + (adjective) + illness

Common Mistakes

She died from a long sickness.
She died from a long illness.
'sickness' often suggests temporary nausea or vomiting in UK English; 'illness' is more neutral for serious or long-term conditions.

2. the condition or time when your body or mind is not working normally and you fee

2.nounA2
Definition

the condition or time when your body or mind is not working normally and you feel unwell

Example

A short illness forced Lucas to stay home from work for three days.

illness as subject: natural for uncountable sense

After a short illness, Elena was able to go back to school.

after a [adjective] illness: time-marker phrase

Common collocations
  • due to illness
  • because of illness
  • after an illness
  • period of illness
  • long illness
  • short illness
  • time off work for illness
Synonyms
  • sickness

    more common in everyday British English for temporary nausea; also used for the general state in American English

  • ill health

    more formal; often used for long-term or chronic conditions

Antonyms
  • health

    the opposite state: when your body and mind are working normally

  • wellness

    more modern or holistic term for positive health

Grammar Patterns

due to illness

period of illness

[adjective] illness

Usage Note

This sense is uncountable and refers to the general experience or period of being unwell, not a named medical condition. To refer to a specific named condition, use sense 1 (e.g. 'He has a rare illness' = specific disease; 'He missed work due to illness' = general state). American English speakers often prefer 'sickness' for the general state; 'illness' is equally natural in both varieties.

Common Mistakes

I have an illness.' (when you mean a cold or headache)
I feel ill.' or 'I'm unwell.
For minor, everyday health problems, 'illness' sounds too serious. Use 'illness' for conditions that last or need medical attention.

Word family

Synonym discussion

Sense: noun/1

illness, disease, sickness, condition, and disorder all refer to health problems, but they differ in formality, scope, and usage. illness is the most general, everyday word for being unwell — it covers both the experience and a named condition. disease is more technical and medical, focusing on the biological process (e.g. heart disease, infectious disease). sickness in British English often means temporary nausea ('motion sickness'), while in American English it works like illness. condition is broad and neutral, often used for ongoing problems ('a heart condition'). disorder is formal and clinical, especially for mental health ('anxiety disorder') or body systems. If you feel generally unwell, say illness. If you need a medical diagnosis, say disease. If a doctor gives a label that is not a classic disease, say condition or disorder.

disease ↗sickness ↗condition ↗disorder ↗

Common collocations

Nouns

  • cause of illness
  • signs of illness
  • treatment of illness
  • symptoms of illness
  • recovery from illness

Adverbs

  • seriously ill
  • critically ill

Phrases

  • suffer from an illness
  • catch an illness
  • recover from an illness
  • die of an illness
  • be off work with illness

Prepositions

  • from illness
  • with illness
  • during illness
  • after illness

Etymology

Old EnglishMiddle EnglishModern English

Illness comes from the Old English word 'yfel' meaning bad or evil, combined with the suffix '-ness' to form a noun. The meaning shifted over time from wickedness to bodily suffering, and by the 1600s it was used for poor health.