drill bit vs trephine

drill bit

noun
  • A twist drill. 

  • Any other style of cutter, for example a spade drill, that is rotated and fed in a similar manner as a twist drill to of cut a hole in metal, wood or other materials. 

trephine

noun
  • A surgical instrument with a cylindrical blade used to remove a circular section of tissue, f.e. bone or cornea; a trepan. 

verb
  • To use a trephine during surgery. 

  • To perforate with a trephine. 

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