quadrillion vs zilliard

quadrillion

noun
  • Any very large number, exceeding normal description. 

num
  • A thousand trillion (logic: 1,000 × 1,000^4): 1 followed by fifteen zeros, 10¹⁵. 

zilliard

noun
  • An unspecified large number (of). 

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