effort vs trephine

effort

noun
  • A force acting on a body in the direction of its motion. 

  • An endeavor. 

  • The work involved in performing an activity; exertion. 

verb
  • To make an effort. 

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 effort and trephine occurred in a corpus of books? (source: Google Ngram Viewer )