approval vs authority

approval

noun
  • An expression granting permission; an indication of agreement with a proposal; an acknowledgement that a person, thing, or event meets requirements. 

  • Something mailed by a seller to a collector to match their stated interests; the collector can approve of or return the item. 

  • An expression of favorable acceptance and encouragement; a compliment that also condones. 

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. 

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