The fictional language used for Galadriel’s song “Namárië” in J.R.R. Tolkien’s The Lord of the Rings is Quenya.
Quenya is one of Tolkien’s principal Elvish languages. He developed it with strong inspiration from Finnish, while also drawing on features of Latin and other languages. In Tolkien’s internal history, it was associated especially with the High Elves and had an elevated, literary status.
“Namárië,” also known as Galadriel’s lament, appears in The Fellowship of the Ring. Its opening and closing words are among the best-known examples of Tolkien’s constructed languages in the published novels.
Sindarin is another major Elvish language and is more commonly spoken by many Elves in Middle-earth. Khuzdul belongs to the Dwarves, while the Black Speech was created for the servants of Mordor. Those distinctions make the song’s language specifically Quenya.