forehead vs proscenium

forehead

noun
  • confidence; audacity; impudence. 

  • The part of the face above the eyebrows and below the hairline. 

  • The upper part of a mobile phone, above the screen. 

proscenium

noun
  • The stage area between the curtain and the orchestra. 

  • The stage area immediately in front of the scene building. 

  • A proscenium arch. 

  • The row of columns at the front the scene building, at first directly behind the circular orchestra but later upon a stage. 

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