stylet vs thumbprint

stylet

noun
  • An engraving tool, a stylus. 

  • A style of a plant's flower. 

  • A slender medical probe or device. 

  • A stiff, slender organ of an animal. 

  • A poniard or stiletto. 

thumbprint

noun
  • A print, mark or impression made by a thumb. 

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