lifeblood vs nub

lifeblood

noun
  • That which is required for continued existence or function. 

  • Blood that is needed for continued life; blood regarded as the seat of life. 

nub

noun
  • The essence or core of an issue, argument etc. 

  • a pointing stick 

  • The clitoris. 

  • A small lump or knob. 

verb
  • To push; to nudge. 

  • To beckon. 

  • To hit the ball weakly. 

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