The Elvish language developed by J.R.R. Tolkien with strong Finnish influence is Quenya.
Quenya is one of Tolkien’s most fully developed constructed languages. He began shaping its earliest forms while studying languages, and Finnish provided important inspiration for its sound and structure. Tolkien also drew on Latin, Greek, and other linguistic traditions.
Within Middle-earth, Quenya is associated with the High Elves and is treated as an ancient, formal language. Sindarin, another major Elvish language, became more widely used in many parts of Middle-earth. Tolkien created histories and relationships between these languages rather than treating them as isolated vocabulary lists.
The famous Elvish inscription on the One Ring is not Quenya alone: its words are in the Black Speech of Mordor, though the script is Tengwar. This distinction often causes confusion among readers learning Tolkien’s languages.