1. A very grumpy, scowling, ill-tempered expression, especially one in which the nose is wrinkled up and the mouth turned down in a frown. His face contorted into an awful sourpuss as he read the review of his performance in the play. What's with all the sourpusses in here? I know we lost, we put up a heck of a fight against the top team in the country!

2. Someone wearing such an expression or having such a mood. Don't be such a sourpuss, Glen. It's not the worst thing that could have happened! I thought the boss was an awful sourpuss when I first started working here, but she's actually really friendly and approachable.