litotes vs onomatopoeia

litotes

noun
  • An ironic figure of speech whereby something is stated by denying its opposite, particularly the negation of a negative quality to say something positive. 

onomatopoeia

noun
  • The property of a word of sounding like what it represents. 

  • The use of language whose sound imitates that which it names. 

  • A word that sounds like what it represents, such as "gurgle," "stutter," or "hiss". 

  • A word that appropriates a sound for another sensation or a perceived nature, such as "thud", "beep", or "meow"; an ideophone, phenomime. 

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