The present Etymological Glossary of Old Welsh is intended to offer an alphabetically arranged list of words which are found in the manuscripts transcribed before the beginning of the Middle Welsh period, and to provide them with the most important published references. Much work has been done both in the field of Old Welsh studies and Celtic lexicography since the puhlication of J. Loth's Vocabulaire vieux-bretolt in 1884 which comprised the then known data of all the early neo-Brittonic languages. Quite a few Old Welsh texts have heen edited anew; more Old Welsh fragments have been found. Notes and articles which analyse specific Old Welsh words and phrases appear in the journals. Old Welsh orthography, phonology, morphology and the rudiments of syntax have been the subjects of dissertations and scholarly research over the course of the twentieth century.