diagonal mark vs incision

diagonal mark

noun
  • Synonym of slash as the forward slash ⟨/⟩ and sometimes also its proscribed sense inclusive of the backslash ⟨\⟩. 

incision

noun
  • A cut-back 

  • The act of cutting into a substance. 

  • 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. 

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