feature film vs seventh art

feature film

noun
  • Any film produced to be shown in cinemas before being released for home viewing. 

  • The main, full-length film in a cinema program that also included a short film and often a newsreel. As of now, it plays after the trailers. 

seventh art

noun
  • Chiefly preceded by the: the art of making motion pictures; filmmaking. 

How often have the words feature film and seventh art occurred in a corpus of books? (source: Google Ngram Viewer )