Ill or sick?

Ill and sick are both adjectives that mean ‘not in good health’. We use both ill and sick 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 …

Note that to be sick means ‘to vomit’ in British English. In American English it means more generally ‘to be unwell’.