1. The fleshy part of either side of the face below the eyes and between the nose and ears: Cora's father kissed his daughter on the cheek.
2. British, informal: impertinent boldness, an attitude, or way of behaving that is ill-mannered and does not show proper respect: Ben had the cheek to insult his hosts at the party.

Sara had the cheek to complain that her efforts to help her friend was not worth the trouble.