exponent vs poster child

exponent

noun
  • One who expounds, represents or advocates. 

  • The part of a floating-point number that represents its exponent value. 

  • The number by which a value (called the base) is said to be raised to a power in exponentiation: for example, the 3 in 2³=8. 

  • A manifestation of a morphosyntactic property. 

poster child

noun
  • One who is a prototypical or quintessential example of something. 

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