A2 [ not usually before noun ] not feeling well, or suffering from a disease生病的，不舒服的
He was very ill for a while but he's all right now.
She felt quite ill from exhaustion.
Don't talk nonsense! She's far too ill to return to work!
It was a shock to see him looking so ill.
Badly cooked shellfish can make you seriously ill.
C1 [ before noun ] formal or old-fashioned bad坏的，恶劣的
to say unkind things about someone说（某人）的坏话
to be a sign of bad things in the future是凶兆，不是好兆头
If you can ill afford to do something, it will cause problems for you if you do it.经不起（做…）；一旦…就会遇麻烦
[ U ] formal or old-fashioned harm坏；伤害
[ C usually plural ] a problem问题，弊病
in a way that is bad or not suitable不好的；不合适的