incision vs oblique stroke

incision

noun
  • The act of cutting into a substance. 

  • A cut-back 

  • A cut, especially one made by a scalpel or similar medical tool in the context of surgical operation; the scar resulting from such a cut. 

oblique stroke

noun
  • Synonym of slash ⟨/⟩. 

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