Other forms: ills
Ill means not well: in bed with a temperature, off work for a week, sitting in a waiting room with a plastic cup of water. She has been ill since Friday. He fell ill on the second day of the holiday.
Ill and sick mean the same thing here but behave differently. British English keeps ill for illness and lets sick mean vomiting, so I feel sick means something is coming up; Americans use sick for both. Ill goes after the verb — she is ill, he looks ill — and sounds wrong in front of a noun, so people say a sick child rather than an ill child. The word's other half means bad or harmful, and it is everywhere in fixed pairs: ill health, ill will, ill effects, ill-treated, ill-equipped, speak ill of the dead. Ill at ease means uncomfortable and on edge. As an adverb it means badly, and it ill becomes you to complain is as formal as English gets.
1adjectiveillNot healthy; suffering from a disease.~49%
“He was too ill to come to the phone.”
synonyms: unwell, poorly
2adjectiveharmfulBad or harmful, used before a noun.~21%
“Years of ill health had worn him down.”
3adverbgoodBadly; in a way that is not good.~28%
“The team was ill prepared for the weather.”
4nounproblemA problem or harm affecting people.~2%
“He blames every ill of the country on the last government.”
Shares are an estimate: a language model read 14 sentences found in the wild and placed 14 of them on a sense — a count of our sample, not a measurement of English.
Also accepted in games: sick, unwell
Ill is not English by birth. It came from Old Norse íllr with the Norse settlers, and in Middle English it meant evil or wicked. That older sense never left: it is still sitting inside ill will, ill deeds and speak ill of the dead. Health is the later job. The trail runs back further to a Proto-Indo-European root that also produced Latin ulcus, a sore, and Greek helkos, a wound.
Proto-Indo-European
*h₁elḱ-
Proto-Germanic
*ilhilaz
Old Norse
íllr
Middle English
ille — evil; wicked
English, today
ill
From Middle English ille (“evil; wicked”), from Old Norse íllr, ílla, ílt, from Proto-Germanic ilhilaz, from Proto-Indo-European h₁elḱ- (whence Latin ulcus (“sore”), Ancient Greek ἕλκος (“wound, ulcer”), Sanskrit अर्शस् (“hemorrhoids”)). 2 Cognate with Scots - and yol ill, Danish ilde (“bad”), Faroese -, Icelandic illur (“bad, ill, wicked”), Norwegian Bokmål -, Norwegian Nynorsk ille (“bad”), Swedish illa (“badly; poorly”).
Etymology from Wiktionary, CC BY-SA