diglot vs multilingual

diglot

adj
  • Synonym of bilingual. 

noun
  • A bilingual inscription, book, or person. 

multilingual

adj
  • Of, relating to, or involving multiple languages. 

  • able to communicate in a number of languages. 

noun
  • a polyglot 

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