knell vs threnode

knell

noun
  • The sound of a bell knelling; a toll (particularly one signalling a death). 

  • A sign of the end or demise of something or someone. 

verb
  • To ring a bell slowly, especially for a funeral; to toll. 

  • To signal or proclaim something (especially a death) by ringing a bell. 

  • To summon by, or as if by, ringing a bell. 

threnode

noun
  • A threne, or threnody; a dirge; a funeral song. 

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