avoirdupois vs ponderosity

avoirdupois

noun

  • Weight; heaviness. 

  • The official system of weights used in the USA between 1866 and 1959. 

  • The official system of weights used in the UK between 1856 and 1963. It had been the customary system in London since 1300. 

ponderosity

noun

  • The quality of requiring extensive thought. 

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