horsepower vs potency

horsepower

noun
  • Strength. 

  • Power derived from the motion of a horse. 

  • A nonmetric unit of power (symbol hp) with various definitions, for different applications. The most common of them is probably the mechanical horsepower, approximately equal to 745.7 watts. 

  • A metric unit (symbol often PS from the German abbreviation), approximately equal to 735.5 watts. 

potency

noun
  • Concentration; strength 

  • Sexual virility: the ability to become erect or achieve orgasm. 

  • Potentiality, ability, capacity. 

  • Power, authority. 

  • The ability or capacity to perform something 

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