In J.R.R. Tolkien’s legendarium, the Dwarves speak Khuzdul.
Khuzdul is the secret language of the Dwarves, who call themselves the Khazâd. Tolkien developed its sound and structure partly with the Semitic languages in mind, contrasting it with the Elvish languages that dominate much of the surviving linguistic material in Middle-earth.
The Dwarves generally keep Khuzdul private and use other languages when communicating with outsiders. Only a small amount of Khuzdul appears in Tolkien’s published narratives, including the battle cry “Baruk Khazâd! Khazâd ai-mênu!”
Quenya and Sindarin are Elvish languages, while Entish is associated with the Ents. Khuzdul should also not be confused with Westron, the common language used by many peoples in the Third Age.