buoyancy vs pessimism

buoyancy

noun
  • Resilience or cheerfulness. 

  • The ability of an object to stay afloat in a fluid. 

  • The upward force on a body immersed or partly immersed in a fluid. 

pessimism

noun
  • A general belief that bad things will happen. 

  • The condition of being pessimal. 

  • The doctrine that this world is the worst of all possible worlds. 

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