encomium vs testimonial

encomium

noun
  • Warm praise, especially a formal expression of such praise; a tribute. 

  • The eighth exercise in the progymnasmata series. 

  • A method within rhetorical pedagogy. 

  • A general category of oratory. 

  • A genre of literature that included five elements: prologue, birth and upbringing, acts of the person's life, comparisons used to praise the subject, and an epilogue. 

testimonial

noun
  • A tribute given in appreciation of someone's service etc. 

  • A statement, especially one given under oath; testimony 

  • A match played in tribute to a particular player (who sometimes receives a proportion of the gate money). 

  • A written recommendation of someone's worth or character 

adj
  • Serving as testimony. 

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