First ancient Celtic languages dictionary of Britain and Ireland underway

Ogham stone, Worthyvale

Ogham stone, Worthyvale

08 December 2025

The first complete dictionary of the ancient Celtic languages of Britain and Ireland is being written by academics at Aberystwyth University.

The modern Celtic languages – Welsh, Irish, Scottish Gaelic, Manx, Breton and Cornish – derive from Celtic languages spoken in these islands before the coming of the Romans to Britain.

The Celtic languages ​​today are quite different from each other, but similarities can be seen between words such as the Welsh ‘môr’ and the Old Irish ‘muir’, which corresponds to ‘Mori-‘ in old British names such as Moridunum ‘Carmarthen’ and Morikambe ‘Morecambe’.

The new dictionary will reveal the diversity and similarities between the Celtic languages of Britain and Ireland up to about the year 500 for the first time.

Dr Simon Rodway, Senior Lecturer in the Department of Welsh and Celtic Studies will lead the work, thanks to a three-year research grant from the Leverhulme Trust.

The project will draw on ancient linguistic evidence from Britain and Ireland, including Celtic place names and personal names recorded in Greek and Latin texts, a handful of Celtic inscriptions from Roman Britain, and the earliest inscriptions from Ireland and Britain using the ‘Ogham alphabet.

Dr Simon Rodway from Aberystwyth University said:

“It’s extremely exciting to lead this project and pen the first dictionary of this kind. These disparate sources have never before been brought together in a way that offers such a comprehensive insight into the nature of Celtic languages spoken in these islands at the dawn of the historical period. It will also show how that evidence compares to the much fuller record from the medieval and modern periods of Welsh, Irish, Scottish Gaelic, Breton, Manx and Cornish.”

The project will also evaluate theories about other languages spoken in Britain and Ireland in prehistory and their connection with the Celtic languages.

Dr Rodway added:

“While it is certain that non-Celtic languages were spoken in these islands before the Celtic languages, and for some time alongside them, we have no uncontroversial direct evidence for those languages, and hypotheses about them range from the cautious to the fanciful. A full collection of the available evidence will allow us to sort the wheat from the chaff.

“The resulting picture of the linguistic landscape of Britain and Ireland in the earliest period will be of huge interest not only to linguists, but also to historians, archaeologists and archaeo-geneticists. This project underlines once again the importance of the Department in Aberystwyth to the study of ancient Celtic, following in the footsteps of and building on the success of important projects on the early Celtic evidence from continental Europe.”