bilingual vs polylingual

bilingual

adj
  • Characterized by the use or presence of two languages. 

  • Hypernym: multilingual 

  • Having the ability to speak two languages. 

  • Spoken or written in two different languages. 

noun
  • A person who is able to use two languages. 

polylingual

adj
  • of or pertaining to multiple languages; multilingual 

  • able to use multiple languages 

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