1especially British Englishsuffering from a disease or not feeling well [= sick American English]COLLOCATIONS COLLOCATIONS feel ill become/fall/get illalso be taken ill make somebody ill seriously/critically/gravely ill (=very ill) chronically ill (=always ill) mentally ill terminally ill (=with an illness you will die from)
spokenused to say that every problem brings an advantage for someone
➔ill feeling, ill willWORD CHOICE: WORD CHOICE: sick, throw up, vomit, ill, not well, unwellIn British English, sick is usually used in the expressions be sick(=have the food in your stomach come up through your mouth) and feel sick (=feel as if this is going to happen)• Someone had been sick on the floor. • Stop it, I feel sick!In American English, you say that someone throws up. Throw up is also used in British English but is fairly informal.Vomit is a fairly formal way to say 'throw up'. If someone has an illness or disease, you usually say that they are ill in British English, and sick in American English• He missed a lot of school when he was ill (BrE)/sick (AmE). In American English, illsuggests you have a more serious disease, from which you may not recover.If someone is slightly ill, you often say in British English that they are not well• I won't come out - I'm not very well.Unwellis a more formal word for 'ill' or 'sick'. ➔ See alsosick
Definition from the Longman Dictionary of Contemporary English Advanced Learner's Dictionary.