groaning vs mourn

groaning

noun
  • A low sound associated with extended suffering, sorrow, and toil. 

adj
  • Heavily laden, as if to creak under the strain. 

  • That groans. 

mourn

noun
  • Sorrow, grief. 

  • A ring fitted upon the head of a lance to prevent wounding an adversary in tilting. 

verb
  • To express sadness or sorrow for; to grieve over (especially a death). 

  • To utter in a sorrowful manner. 

  • To wear mourning. 

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