rivet vs underpinning

rivet

noun
  • Any fixed point or certain basis. 

  • A cylindrical mechanical fastener that attaches multiple parts together by fitting through a hole and deforming the head(s) at either end. 

verb
  • To command the attention of. 

  • To attach or fasten parts by using rivets. 

  • To make firm or immovable. 

  • To install rivets. 

underpinning

noun
  • A basis for something. 

  • The lower body or legs. 

  • A support or foundation, especially as a structure of masonry that supports a wall. 

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