Feel sick Definition 1 of 3Pro Tip 1/3Physical Discomfort Used to express actual feelings of nausea or potential illness. I feel sick and might need to see a doctor. Pro Tip 2/3Mild Complaint Not always serious, can be a casual remark after overeating or discomfort. Oops, I feel sick from all the dessert I ate. Pro Tip 3/3Temporary State Often suggests a short-term feeling that may soon pass. I just need to rest; I'll feel sick for a bit.