What is difference between Ill and Sick, How do I say "sick people" or "ill people" to refer to people not feeling well?

  • ill used before a noun means bad or harmful : the neglect and ill treatment of children.....unable to join the army because of ill health... an ill omen...harbor no ill intentions toward them. Dec 5 '17 at 18:39

Honestly, I was not aware of the differences between both either; however, after searching for it for a while, I found out some interesting differences between both:


  • Is normally used to refer to long-term diseases, such as cancer, pneumonia and etc..

  • Can never be used attributively (before the noun) - ex: ill child. Instead, it can only be used postpositively (after the noun) or predicatively (after a linking or copula verb) ex: A child ill - He seems ill.

  • Ill also works as a prefix when implying something made in a bad manner: The ill-painting of my house, we should have never employed that guy!


  • Is an informal and short term, usually refers to short sickness such as one that unables you to go to school for one or two days.

  • Can be used attributively, postpositively and predicatively, ex: I saw a sick child; the child sick; the child seems sick.

  • 1
    But interestingly, "ill" is sometimes used before a noun when it is used metaphorically. "It's an ill wind that blows no good." "Ill-gotten gains", etc.
    – Jay
    Dec 5 '17 at 20:35
  • Interesting, Jaw. You also reminded me of adding the fact that "ill" also works as a suffix when implying something made in a bad way. I will add it up on my answer.
    – Davyd
    Dec 5 '17 at 20:56
  • I've never seen unables used like that. Even Scrabble does not allow it, yet the meaning is quite clear. Interesting.
    – Davo
    Dec 5 '17 at 22:55
  • @Davo - Cambridge cites such uses of the prefix ill: dictionary.cambridge.org/dictionary/english/ill
    – Davyd
    Dec 5 '17 at 23:17
  • 1
    @Davo Able and unable are not verbs. Conjugating unable as if it were a transitive verb is kind of fun and interesting, but of course, the standard word to use there would be "disables." And then you'd use "from" as the preposition. Dec 5 '17 at 23:27

Sick and ill are both adjectives that mean ‘not in good health’. We use both sick and ill after a verb such as be, become, feel, look or seem:

I was ill for a time last year, but I’m fine now.

Nancy looks ill. I wonder what’s wrong with her.

I felt sick and had to go home at lunchtime.

We can use sick before a noun but we don’t normally use ill before a noun:

She’s been looking after a sick child this week, so she’s not at work.

Not: … an ill child …

In American English sick means more generally ‘to be unwell’.

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