The fictional language family containing Quenya and Sindarin is Tolkien’s Elvish languages.
Tolkien created several related Elvish languages for the peoples of Middle-earth. Quenya and Sindarin are the best known: Quenya is associated especially with the High Elves, while Sindarin became the everyday Elvish language of many Elves in Middle-earth. Their histories, sound patterns, and vocabulary reflect Tolkien’s training as a philologist.
The phrase “Elvish languages” describes a group rather than one single tongue. Tolkien also developed languages such as Telerin and Noldorin, the earlier form connected to Sindarin in his evolving linguistic work. This is why Elvish should not be treated as a synonym for Quenya alone. The languages changed across Tolkien’s drafts, but their internal relationships remained a central part of his world-building.