awl vs trepan

awl

noun
  • A pointed instrument for piercing small holes, as in leather or wood; used by shoemakers, saddlers, cabinetmakers, etc. The blade is differently shaped and pointed for different uses, as in the brad awl, saddler's awl, shoemaker's awl, etc. 

  • Any of various hesperiid butterflies. 

trepan

noun
  • A tool used to bore through rock when sinking shafts. 

  • A surgical instrument used to remove a circular section of bone from the skull; a trephine. 

verb
  • To create a large hole by making a narrow groove outlining the shape of the hole and then removing the plug of material remaining by less expensive means. 

  • To use a trepan; to trephine. 

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