In J.R.R. Tolkien’s legendarium, in which language is the Ring-inscription written?

The Ring-inscription in J.R.R. Tolkien’s legendarium is written in the Black Speech of Mordor.

The inscription appears on the One Ring in fiery letters when the Ring is heated. Its two lines are the opening of a verse describing the Rings of Power: one ring to rule the others, bind them, and bring them into the darkness of Mordor.

Tolkien created the Black Speech for Sauron and the servants of Mordor. The inscription is not written in Quenya, the High-elven language, or Sindarin, a major Elvish language of Middle-earth. Those languages are associated with different peoples and histories.

The Ring’s lettering is also linked to Tengwar, the script used to write it. Language and script are separate concepts here: the language is the Black Speech, while the visible characters belong to an Elvish writing system.