Westron (called Adûni in Westron, or Sôval Phârë, meaning "Common Speech") is the constructed language that was supposedly the Common Speech used in J. R. R. Tolkien's world of Middle-earth in the Third Age, at the time of The Lord of the Rings. It ostensibly developed from Adûnaic, the ancient language of Númenor. In practice in the novel, Westron is nearly always represented by modern English, in a process of pseudo-translation which also sees Rohirric represented by Old English. That process allowed Tolkien not to develop Westron or Rohirric in any detail. In the Appendices of the novel, Tolkien gives some examples of Westron words.

From his schooldays, J. R. R. Tolkien was, in the words of his biographer John Garth, "effusive about philology"; his schoolfriend Rob Gilson called him "quite a great authority on etymology".^[2] Tolkien was a professional philologist, a scholar of comparative and historical linguistics. He was especially familiar with Old English and related languages. He remarked to the poet and The New York Times book reviewer Harvey Breit that "I am a philologist and all my work is philological"; he explained to his American publisher Houghton Mifflin that this was meant to imply that his work was "all of a piece, and fundamentally linguistic in inspiration. ... The invention of languages is the foundation. The 'stories' were made rather to provide a world for the languages than the reverse. To me a name comes first and the story follows."^{[T 1]}

Tolkien created a large family of Elvish languages, the best-known and most developed being Quenya and Sindarin.^[3] In addition, he sketched in the Mannish languages of Westron's precursor, Adûnaic, and Rohirric;^[4] the Dwarvish language of Khuzdul;^{[T 2]} the Entish language;^{[T 3]} and the Black Speech of the Orcs.^{[T 4]}

When writing The Lord of the Rings (1954–55), a sequel to The Hobbit (1937), Tolkien came up with the literary device of using real languages to "translate" fictional languages. He pretended that he had not composed the book himself but had translated it from Westron (named Adûni in Westron) or Common Speech (Sôval Phârë, in Westron) into English. The purpose of this was to provide an explanation for why the Common Speech is almost entirely rendered as English in the novel. This device of rendering an imaginary language with a real one was carried further by rendering:^[1]

• Rohirric, the language of Rohan (related to Westron) by the Mercian dialect of Old English;^[1]
• names in the tongue of Dale by Old Norse forms;^[1]
• names of the Kingdom of Rhovanion by Gothic forms, thus mapping the genetic relation of his fictional languages on to the existing historical relations of the Germanic languages.^[1]

The whole device of linguistic mapping was essentially a fix for the problems Tolkien had created for himself by using real Norse names for the Dwarves in The Hobbit, rather than inventing new names in Khuzdul, the language of the Dwarves. This seemed a clever solution, as it allowed him to explain the book's use of Modern English as representing Westron.^[5] Because of this, Tolkien did not need to develop Westron grammar or vocabulary in any detail.^[6]

Tolkien went further, using Gothic names for the early leaders of the Northmen of Rhovanion, ancestors of Rohan, and for the first Kings of Rohan.^{[T 6][7]} Gothic was an East Germanic language, and as such is a forerunner of Old English, not a direct ancestor.^[8] Christopher Tolkien suggests that his father intended the correspondence between the language families to extend back to the ancestral language of the Northmen.^{[T 6]}

Westron (also called Adûni) supposedly developed from Adûnaic, the ancient language of Númenor.^{[T 8]} It became the lingua franca for all the peoples of Middle-earth:^[9] Tolkien gives some examples of Westron words in Appendix F to The Lord of the Rings, where he summarizes Westron's origin and role as lingua franca in Middle-earth:^{[T 3]}

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