buoy vs pluck up

buoy

verb
  • To maintain or enhance enthusiasm or confidence; to lift the spirits of. 

  • To support or maintain at a high level. 

  • To keep afloat or aloft; used with up. 

  • To mark with a buoy. 

noun
  • A life-buoy; a life preserver. 

  • A float moored in water to mark a location, warn of danger, indicate a navigational channel or for other purposes 

pluck up

verb
  • To summon positive emotion (especially courage); to muster. 

  • To remove or acquire by plucking from, for example, the ground; to pick up. 

  • To become more cheerful. 

How often have the words buoy and pluck up occurred in a corpus of books? (source: Google Ngram Viewer )