The Elvish language often called High-elven in J.R.R. Tolkien’s fiction is Quenya.
Quenya is one of Tolkien’s most fully developed invented languages. Within the mythology, it is associated especially with the High Elves and draws inspiration from the sound and structure of languages such as Finnish, Greek, and Latin. Tolkien developed vocabulary, grammar, and historical changes rather than creating only a collection of decorative words.
Quenya appears in names, poems, inscriptions, and formal speech throughout Tolkien’s legendarium. The language’s fictional history includes changes caused by the separation and migrations of Elvish peoples. Its status also changes over time: in Middle-earth it functions largely as an ancient or ceremonial language.
Sindarin is another major Elvish language and is more commonly used by many Elves in The Lord of the Rings. Quenya and Sindarin are therefore related but distinct, not interchangeable labels for one language.