1. phrasal verb If you buck someone up or buck up their spirits, you say or do something to make them more cheerful. [British, informal] [V n P] ⇒ Anything anybody said to him to try and buck him up wouldn't sink in. [VP n] ⇒ The aim, it seemed, was to buck up their spirits in the face of the recession. 2. phrasal verb → buck 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] [VP] ⇒ People are saying if we don't buck up we'll be in trouble. [VP n] ⇒ Buck up your ideas or you'll get more of the same treatment.
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