1. An exaggerated frown, scowl, or sullen expression (as if reacting to the briny flavor of pickle juice). What's with the picklepuss? We're on vacation—lighten up! The president's famous picklepuss appeared the moment the British Prime Minister began talking about the proposed trade agreement during the conference.

2. Someone who wears such an expression frequently or constantly. We threw a surprise birthday party for Bill, but the picklepuss that he didn't even smile. Don't be such a picklepuss, darling. We're at a party, so stop worrying about work and try to enjoy yourself.