souvenir vs testimonial

souvenir

noun
  • An item of sentimental value, that is given or kept to remember an event or location. 

verb
  • To take (something) as a souvenir, especially illicitly, for example during wartime. 

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 souvenir and testimonial occurred in a corpus of books? (source: Google Ngram Viewer )