J.R.R. Tolkien’s academic field at Oxford, specializing in Old and Middle English, was philology.
Philology studies language through historical texts, including how words, sounds, and grammatical forms change. Tolkien’s professional work focused especially on Germanic languages and medieval literature. His expertise in Old English, Middle English, Old Norse, Welsh, Finnish, and other languages informed both his scholarship and his invented languages.
At Oxford, Tolkien held several academic posts. He was Rawlinson and Bosworth Professor of Anglo-Saxon from 1925 to 1945 and Merton Professor of English Language and Literature from 1945 until his retirement in 1959. His scholarly work included the influential lecture later published as Beowulf: The Monsters and the Critics.
Philology is sometimes reduced to “studying old languages,” but Tolkien treated language, literature, history, and culture as closely connected. That approach helped shape the depth and internal history of Middle-earth.