documental vs documentary

documental

documentary

noun
  • A film, TV program, publication etc. which presents a social, political, scientific or historical subject in a factual or informative manner. 

adj
  • Of, related to, or based on documents. 

  • Which serves to document (record and:or illustrate) a subject. 

  • Presented objectively without the insertion of fictional matter. 

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