lamentation vs threnode

lamentation

noun
  • lamentatio, (part of) a liturgical Bible text (from the book of Job) and its musical settings, usually in the plural; hence, any dirge 

  • Specifically, mourning. 

  • The act of lamenting. 

  • A sorrowful cry; a lament. 

  • A group of swans. 

threnode

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

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