mourn vs ululate

mourn

verb
  • To utter in a sorrowful manner. 

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

  • To wear mourning. 

noun
  • Sorrow, grief. 

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

ululate

verb
  • to howl loudly or prolongedly in lamentation or joy 

  • to produce a rapid and prolonged series of sharp noises with one's voice. 

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