For which reference work did J.R.R. Tolkien work as an assistant between 1919 and 1920?

J.R.R. Tolkien worked as an assistant on The Oxford English Dictionary between 1919 and 1920.

After serving in the First World War, Tolkien joined the staff working on the dictionary, then known as the New English Dictionary. He was assigned to the “W” section and helped research the histories and relationships of words. This early professional experience gave him practical training in historical linguistics and philology.

Tolkien later became an academic and a celebrated author, but his dictionary work is an important part of his scholarly background. His interest in word origins, sound changes, and the development of languages also shaped his invented languages and the names in his fiction. The dictionary is sometimes confused with Tolkien’s university teaching, but this was a separate early job before his long Oxford academic career.