Gobbledegook is the native language of the Goblins. Barty Crouch Sr., Dirk Cresswell, and Albus Dumbledore are known non-Goblin speakers. There is only one word of Gobbledegook specifically stated in the series, bladvak, which, according to Ludo Bagman, means pickaxe.
During the series it has been spoken two times: in The Three Broomsticks, by two goblins defrauded by Ludo; and by Dirk Cresswell and the goblins Gornuk and Griphook, during their leak from the Snatchers.
It has been described as a harsh, rasping language, which makes it sound distinctly inhuman.
Gobbledegook, or Gibberish, are words that are nonsense.