focal point vs nub

focal point

noun
  • The centre of any activity. 

  • A solution that people will tend to use in the absence of communication, because it seems natural, special, or relevant. 

  • A focus; a point at which rays of light or other radiation converge. 

  • A feature that attracts particular attention. 

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 focal point and nub occurred in a corpus of books? (source: Google Ngram Viewer )