Unwell/ʌnˈwel/ Definition 1 of 2Pro Tip 1/3Physical Discomfort Use 'unwell' when someone doesn't feel physically healthy, but it's not very serious. I felt unwell after eating too much cake. Pro Tip 2/3Mild Illness 'Unwell' often hints at a mild illness rather than a severe one. She's been unwell with a bit of a fever. Pro Tip 3/3Short-term Condition It generally suggests a temporary condition, not a long-term health issue. He's unwell today, probably will be fine by tomorrow.