gibberish vs intelligibility

gibberish

adj
  • unintelligible, incoherent or meaningless 

noun
  • Needlessly obscure or overly technical language. 

  • Speech or writing that is unintelligible, incoherent or meaningless. 

  • A language game, comparable to pig Latin, in which one inserts a nonsense syllable before the first vowel in each syllable of a word. 

intelligibility

noun
  • The quality of recorded speech of every word being understandable. 

  • That which is intelligible; the degree to which something is intelligible. 

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