ill
ihl
Ill (adjective) means Unwell or in poor health; sick. Example: “After eating the shellfish, the whole family fell ill during the night.”
adjective
1
Unwell or in poor health; sick.
"After eating the shellfish, the whole family fell ill during the night."
"She stayed home from work because she felt ill."
"He was seriously ill for most of last winter."
2
Bad, harmful, or unfavourable.
"He wished no ill will toward his old rivals, despite the argument."
"The villagers believed the broken mirror was an ill omen for the journey."
"The decision had some unexpected ill effects on morale."
adverb
1
Badly or imperfectly.
"The tiny coat fitted him ill, with sleeves far too short."
"She was ill prepared for the sudden change in the weather."
"The plan was ill conceived from the very start."
noun
1
A problem, hardship, or misfortune (usually plural).
"The charity works to cure the ills of the neighbourhood, one street at a time."
"Doctors in the village treated all kinds of ills with simple herbal remedies."
"The report examined the social ills of poverty and unemployment."
How to use ill
Learner’s notesIn plain EnglishMost commonly means "sick," but as an adverb/prefix it also means "badly" (ill-advised, ill-timed).
UK vs US
British English uses "ill" for "sick" more often in everyday speech than American English, which tends to prefer "sick."
Common pairings
fall ill
critically ill
ill health
ill-advised
social ills
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Word forms
- Plural
- ills
- Third person singular
- ills
- Past tense
- illed
- Comparative
- iller, more ill, worse
- Superlative
- illest, most ill, worst
Fill the gap
Can you complete this real example?
After eating the shellfish, the whole family fell _____ during the night.
Etymology
From Old Norse illr, "bad, evil," related to Danish ilde and Swedish illa.
Synonyms
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Related words
Rhymes for ill
See all rhymes for ill →Frequently asked questions
What does “ill” mean?
The word “ill” means unwell or in poor health; sick. In plain terms, most commonly means "sick," but as an adverb/prefix it also means "badly" (ill-advised, ill-timed).
How do you pronounce “ill”?
“Ill” is pronounced ihl (/ɪl/ in IPA).
How do you use “ill” in a sentence?
Here is “ill” used in a sentence: “She stayed home from work because she felt ill.”
What is another word for “ill”?
Words with a similar meaning to “ill” include bad, mal-, crank, crook, green about the gills and icky.
What is the opposite of “ill”?
The opposite of “ill” — its antonyms — are fine, hale, healthy, in good health and well.
What part of speech is “ill”?
Depending on how it is used, “ill” can be an adjective, an adverb and a noun.
Where does the word “ill” come from?
The word “ill” comes from Old Norse. From Old Norse illr, "bad, evil," related to Danish ilde and Swedish illa.
Is “ill” a common word?
“Ill” is a very common word in modern English, usually learned at around the A2 level.
What is the difference between ill and sick?
Ill and sick both mean unwell, and in most contexts they are interchangeable. British English tends to prefer "ill" for being unwell, reserving "sick" for the sense of vomiting; American English uses "sick" more broadly for any illness. "Ill" can also sound slightly more formal or more serious.
Does ill always mean sick?
No. Besides meaning unwell, "ill" can mean bad, harmful, or hostile, as in "ill will," "ill effects," "ill-advised," or "speak ill of someone." As an adverb it means badly, as in "ill-equipped." As a noun, "ills" are troubles or problems. The unwell sense is simply the most familiar.
Is ill formal or informal?
"Ill" is neutral to slightly formal and works in both everyday and professional writing. In British English it is the standard word for being unwell, where American English often prefers "sick." It fits comfortably in phrases like "seriously ill" or "taken ill," carrying a measured, matter-of-fact tone.
What is the opposite of ill?
When "ill" means unwell, its opposite is "well" or "healthy" — you might say someone is "well again" after recovering. Other antonyms include "fit," "sound," and "in good health." When "ill" means harmful, as in "ill effects," the opposite shifts to "good" or "beneficial."
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