navel vs rivet

navel

noun
  • The central part or point of anything; the middle. 

  • An eye on the underside of a carronade for securing it to a carriage. 

  • The indentation or bump remaining in the abdomen of mammals where the umbilical cord was attached before birth. 

  • A navel orange. 

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. 

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