impotence vs voltage

impotence

noun
  • Inability to copulate or beget children; sterility, erectile dysfunction, etc. 

  • Powerlessness; incapacity. 

voltage

noun
  • The difference in electrostatic potential between two points in space, especially between live and neutral conductors or the earth. 

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