approval vs protestation

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. 

protestation

noun
  • A declaration in common-law pleading, by which the party interposes an oblique allegation or denial of some fact, protesting that it does or does not exist, and at the same time avoiding a direct affirmation or denial. 

  • a formal solemn objection or other declaration 

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