authority vs power of attorney

authority

noun
  • Official permission; authorisation to act in some capacity on behalf of a ruling entity. 

  • A reliable, definitive source of information on a subject. 

  • Persons, regarded collectively, who occupy official positions of power; police or law enforcement. 

  • A government-owned agency that runs a revenue-generating activity for public benefit. 

  • Status as a trustworthy source of information, reputation for mastery or expertise; or claim to such status or reputation. 

  • Power or right to make or enforce rules or give orders; or a position having such power or right. 

power of attorney

noun
  • The legal authorisation of one person to act as the agent of another. 

  • A legal document allowing one person to act as the agent of another. 

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