One of the mysteries of the English language finally explained.
Synonyms of documentary in English:
documentary
See definition of documentary
adjective
1‘there is documentary evidence that a corn mill stood here in the 14th century’
SYNONYMS
recorded, documented, registered, written, chronicled, archived, archive, on record, in writing, on paper
tabulated, charted
2‘the event will be the subject of a documentary film’
SYNONYMS
factual, non-fictional, real-life, true to life, fact-based
ANTONYMS
fictional
noun
1‘the BBC showed a documentary about life in rural England’
SYNONYMS
factual programme, factual film
programme, film, report, presentation, broadcast, transmission