What was the original name of Moria in J.R.R. Tolkien’s legendarium?

The original name of Moria in J.R.R. Tolkien’s legendarium was Khazad-dûm.

Khazad-dûm is the great underground Dwarven city and kingdom beneath the Misty Mountains. Its name is in Khuzdul, the secret language of the Dwarves, and means “Dwarves’ Digs” or “Dwarves’ Mansion” in Tolkien’s constructed-language notes.

The kingdom became famous for its wealth, especially mithril, a precious metal found in the mines. The Dwarves awakened a Balrog while mining too deeply, and the settlement was abandoned after the disaster. In the Third Age, the ruined city was more commonly known as Moria.

Moria is not the name the Dwarves originally used for their home. It is an Elvish name meaning “Black Chasm” or “Black Pit,” reflecting the later fear and darkness associated with the abandoned realm.