Rueful means feeling or showing regret tinged with amusement or wry acceptance. When you make a rueful face, you're acknowledging that you messed up or that something didn't work out, but you're not devastated about it. There's a slightly humorous edge to it, like you can see the irony or absurdity of the situation.

Picture a student who studied the wrong chapter for a test. She might give a rueful smile when she realizes her mistake: disappointed, yes, but also slightly amused at her own oversight. Or imagine a basketball player who misses an easy shot in the final seconds. His rueful expression says “I can't believe I did that” with a touch of self-aware humor rather than bitter anger.

The feeling combines regret with a kind of gentle self-mockery. It's lighter than shame and less intense than remorse. When someone laughs ruefully at their own blunder, they're showing they can recognize their mistake without taking themselves too seriously. A rueful shake of the head often means “Well, that didn't go as planned, did it?”