E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Rude, uncouth, unknown; as a Caliban style, a Caliban language. The allusion is to Shakespeares Caliban (The Tempest), in which character Lord Falkland, etc., said that Shakespeare had not only invented a new creation, but also a new language.
Satan had not the privilege, as Caliban, to use new phrases, and diction unknown.Dr. Bentley.
Coleridge says, In him [Caliban, as in some brute animals, this advance to the intellectual faculties, without the moral sense, is marked by the appearance of vice.
(Caliban is the missing link between brute animals and man.)