Welsh was a major phonological inspiration for J.R.R. Tolkien’s Sindarin.
Tolkien admired the sound of Welsh and used it as an important influence when developing Sindarin, the language most commonly spoken by Elves in the regions of Middle-earth depicted in The Lord of the Rings. Sindarin was designed as part of a larger historical family of Elvish languages, not as a simple code for English.
The language’s fictional history connects it to earlier forms such as Common Eldarin and Old Sindarin. Tolkien created patterns of sound change so that related languages would resemble one another while still having distinct identities. This approach reflected his professional interest in historical linguistics.
Quenya, another prominent Elvish language, was influenced especially by Finnish and Latin. The two languages therefore have different aesthetic and historical profiles within Tolkien’s mythology. Sindarin’s Welsh influence is most visible in its phonology and overall sound, rather than in a direct one-to-one translation of Welsh vocabulary.