The cheek is the soft, fleshy part of your face between your ear and mouth, on either side of your nose. You can feel your cheeks puff out when you blow air into them, or notice how they might turn red when you're embarrassed or have been running hard.

The word also describes bold, playful rudeness that somehow doesn't quite cross the line into serious disrespect. When someone has cheek, they're being sassy or slightly impertinent, but usually in a way that's more amusing than offensive. If you tell your teacher, “That assignment was surprisingly easy for someone as brilliant as me,” with a grin, you're showing cheek. Your teacher might respond, “What cheek!” recognizing that you're being cheeky rather than genuinely arrogant.

The phrase tongue in cheek means you're not being serious, even though your words might sound serious. If your friend says with a completely straight face, “I'm devastated that we have no homework this weekend,” they're speaking tongue in cheek, meaning the opposite of what they're saying. It's the verbal equivalent of a wink, letting others know you're joking without actually saying so.