flap vs proscenium

flap

noun
  • A side fin of a ray. 

  • A consonant sound made by a single muscle contraction, such as the sound /ɾ/ in the standard American English pronunciation of body. 

  • The motion of anything broad and loose, or a sound or stroke made with it. 

  • Anything broad and flexible that hangs loose, or that is attached by one side or end and is easily moved. 

  • A piece of tissue incompletely detached from the body, as an intermediate stage of plastic surgery. 

  • A hinged leaf. 

  • The labia, the vulva. 

  • A hinged surface on the trailing edge of the wings of an aeroplane, used to increase lift and drag. 

  • A controversy, scandal, stir, or upset. 

verb
  • To move loosely back and forth. 

  • To move (something broad and loose) up and down. 

  • Of a resource or network destination: to be advertised as being available and then unavailable (or available by different routes) in rapid succession. 

proscenium

noun
  • A proscenium arch. 

  • The stage area between the curtain and the orchestra. 

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

  • 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 flap and proscenium occurred in a corpus of books? (source: Google Ngram Viewer )