In J.R.R. Tolkien’s legendarium, Adûnaic was the language associated with the people of Númenor. Tolkien described it as the native tongue of the Númenóreans, who were descended from the Men who had allied with the Elves during the First Age.
Adûnaic belongs to Tolkien’s invented linguistic history rather than being a language spoken by Elves. In the fictional chronology, Númenor’s people also encountered and used Elvish languages, including Quenya and Sindarin. After Númenor’s destruction, forms of its speech influenced the Common Speech and related tongues of Middle-earth.
The name is often confused with Quenya or Sindarin because those are the best-known languages in Tolkien’s mythology. Quenya was associated especially with the High Elves, while Sindarin was widely used by Elves in Middle-earth. Khuzdul, by contrast, was the secret language of the Dwarves. Adûnaic is specifically tied to Númenor and its Men.