The Elvish language Tolkien developed for the High Elves is Quenya.
Quenya is one of Tolkien’s most fully developed constructed languages. He based much of its sound and structure on Finnish, while also drawing on his wide knowledge of historical linguistics. In Tolkien’s mythology, Quenya was associated especially with the Ñoldor and other Elves who had lived in Valinor.
The language appears in names, poetry, formal speech, and inscriptions throughout Tolkien’s legendarium. Familiar examples include Eärendil, Galadriel, and the greeting “Elen síla lúmenn’ omentielvo,” although Tolkien’s published texts do not present a complete everyday language in the modern sense.
Quenya is often confused with Sindarin, another major Elvish language. Sindarin became the more widely spoken Elven tongue in much of Middle-earth, while Quenya generally carried an older, more ceremonial status.