J.R.R. Tolkien invented Khuzdul as the speech of the Dwarves.
Khuzdul is the secret language associated with the Dwarves in Tolkien’s legendarium. The Dwarves call themselves Khazâd, and their language is described as something they generally kept private from other peoples. Tolkien modeled parts of its sound and structure on Semitic languages, especially in its consonantal patterns.
Only a small amount of Khuzdul appears in Tolkien’s published writings. One famous example is the inscription on the West-gate of Moria, which includes the greeting “speak, friend, and enter” in Elvish rather than Khuzdul. The Dwarves’ own name for the chambered realm is Khazad-dûm.
Khuzdul should not be confused with Quenya or Sindarin, which are Elvish languages, or the Black Speech, which Sauron created for servants of Mordor. Its limited surviving vocabulary is part of what makes it difficult to study fully.