multifold vs myriad

multifold

adj
  • Many; very diverse; manifold. 

myriad

adj
  • Multifaceted, having innumerable elements 

  • Great in number; innumerable, multitudinous 

noun
  • A countless number or multitude (of specified things) 

  • Ten thousand; 10,000 

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