prodigious vs unheard-of

prodigious

adj
  • Extraordinarily amazing or exciting. 

  • Very big in size or quantity; colossal, gigantic, huge. 

  • Freakish; monstrous. 

unheard-of

adj
  • Previously unknown; unprecedented. 

  • Unknown or known to only few people. 

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