Collins COBUILD Advanced Learner's English Dictionary - buck up

1. If you buck someone up or buck up their spirits, you say or do something to make them more cheerful. (BRIT INFORMAL) Anything anybody said to him to try and buck him up wouldn’t sink in... The aim, it seemed, was to buck up their spirits in the face of the recession. = cheer up PHRASAL VERB: V n P, V P n (not pron) 2. If you tell someone to buck up or to buck up their ideas, you are telling them to start behaving in a more positive and efficient manner. (INFORMAL) People are saying if we don’t buck up we’ll be in trouble... Buck up your ideas or you’ll get more of the same treatment. = pull one’s socks up PHRASAL VERB: V P, V P n (not pron)