brainbox vs caput

brainbox

noun
  • The head or skull (which encloses the brain). 

  • A very intelligent person. 

caput

noun
  • The head. 

  • A knob-like protuberance or capitulum. 

  • The top or superior part of a thing. 

  • The council or ruling body of the University of Cambridge prior to the constitution of 1856. 

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