diction vs inarticulation

diction

noun
  • Choice and use of words, especially with regard to effective communication. 

  • Enunciation, pronunciation. 

  • The effectiveness and degree of clarity of word choice and expression. 

inarticulation

noun
  • The state of being inarticulate; inarticulateness. 

  • An inarticulate or underarticulated utterance. 

  • Any point in the educational system in which the development of the individual is hindered. 

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