adjective (a)

• without or deprived of the use of speech or words(adj.all)

  Example:
  Inarticulate beasts.
  Remained stupidly inarticulate and saying something noncommittal.
  Inarticulate with rage.
  An inarticulate cry.
  

  Synonym:
  unarticulate
  Antonym:
  articulate
  

  source: wordnet30
• Not uttered with articulation or intelligible distinctness, as speech or words.(adjective)

  source: webster1913