The word sick has several meanings:

1. Ill or unwell. When you're sick, your body isn't working properly. You might have a fever, a sore throat, or an upset stomach. Students who feel sick often stay home from school to rest and recover. Doctors help sick patients get better by diagnosing what's wrong and recommending treatment.
2. Disgusted or nauseated. If something makes you feel sick to your stomach, it's so unpleasant that it makes you want to throw up. Seeing spoiled food or smelling something rotten might make you feel sick. People also say they're sick of something when they're tired of it and can't stand it anymore, like being sick of rainy weather after two weeks straight.
3. In modern slang, extremely cool or impressive. When someone says, “that skateboard trick was sick,” they mean it was amazing. A sick guitar solo or a sick goal in soccer shows exceptional skill. This meaning is the opposite of the others, so pay attention to context and tone of voice to know which meaning someone intends.