J.R.R. Tolkien’s academic field, centered on the history of languages, was philology.
Philology is the historical study of languages through texts, including changes in vocabulary, grammar, pronunciation, and writing. Tolkien trained and worked as a philologist, specializing particularly in Germanic languages and medieval literature. This discipline provided the scholarly foundation for both his teaching and his creative work.
Tolkien’s interest in invented languages began before The Hobbit and The Lord of the Rings became famous. He developed languages such as Quenya and Sindarin with attention to sound patterns, historical relationships, and internal change. He then imagined peoples and histories that could explain how those languages developed.
Philology is not the same as linguistics in every modern academic sense, although the fields overlap. Tolkien’s work is also often called mythology or fantasy literature because of his fiction, but those labels describe his creative output rather than his university specialization.