Your cheek is the part of your face under your eye and between your ear and nose. Your cheeks might turn bright red in embarrassment when you have to speak in public.
When you cry, your cheeks get wet, and when you greet your grandmother, she might give you a kiss on the cheek or even pinch your cheek. Informally, your cheeks are also your buttocks or bottom — and when you're a little rude or sassy, your attitude itself can be called cheek. It comes from the Old English word ceace, "jaw," which probably stems from ceowan, "chew."