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)