approbative vs complimentary

approbative

adj
  • Expressing approval. 

  • Sanctioning officially, giving authorization or approval to something. 

noun
  • A word or grammatical form which denotes a positive affect expressing the appreciation or approval of the speaker. 

complimentary

adj
  • In the nature of a compliment. 

  • With respect to the closing of a letter, formal and professional. 

  • Free; provided at no charge. 

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