J.R.R. Tolkien named the constructed language spoken by many Elves in Valinor Quenya.
Quenya is one of Tolkien’s most developed Elvish languages. He based much of its sound and structure on Finnish, while also connecting it to his invented history of the Elves. In Middle-earth, Quenya was associated especially with the High Elves and was often treated as a formal, literary, or ceremonial language rather than the everyday speech of most Elves.
Sindarin is the main competing answer because it is another major Elvish language and became more common in Middle-earth. Tolkien linked Sindarin’s sound chiefly with Welsh. The two languages belong to the same fictional linguistic family but are not interchangeable.
Tolkien’s language-building began before many of his published stories. He often created languages first and then developed peoples, histories, and myths that would give those languages a setting and purpose.