Tolkien invented Valarin as the language of the Valar.
Valarin is the language associated with the Valar, the powerful spiritual beings who inhabit and shape Arda in Tolkien’s mythology. It is described as being difficult for the Elves to understand and unlike the languages that later developed among the peoples of Middle-earth.
Tolkien’s interest in language was central to his creative method. He studied historical languages and constructed languages with their own sound patterns, word histories, and relationships. The better-known Elvish languages Quenya and Sindarin are connected to the linguistic history of the Elves, not to the Valar themselves.
Valarin appears mainly in linguistic notes and mythological material associated with The Silmarillion and related posthumously published writings. Because Tolkien created many languages, readers sometimes identify Sindarin or Quenya as the language of every supernatural people. Those languages are prominent, but Valarin is the specifically Valar-associated answer.