First Ever Ancient Celtic Dictionary Compiled by UK Linguists

Published: 08 December 2025. The English Chronicle Desk. The English Chronicle Online.

A groundbreaking linguistic project has quietly begun in west Wales that promises to shine new light on the voices of people who walked Britain and Ireland more than two thousand years ago. Scholars at Aberystwyth University have started work on what they believe will be the world’s first complete dictionary of the ancient Celtic language spoken across these islands before the Romans, Anglo-Saxons, and Vikings reshaped the linguistic map.

The finished book will not resemble the thick volumes we associate with modern dictionaries. Most of the language vanished long ago, swallowed by time and conquest. Yet the surviving fragments, scattered through Roman records, ancient place-names, and weathered stone inscriptions, are now being gathered with meticulous care. Researchers expect the final work to contain just over one thousand words, a modest total that nevertheless represents a treasure recovered from the edge of oblivion.

Dr Simon Rodway, a senior lecturer in Welsh and Celtic studies who leads the project, can barely contain his enthusiasm when he speaks about the task ahead. For the first time, every known scrap of ancient Celtic from Britain and Ireland will appear between two covers, or rather on one comprehensive digital platform alongside a printed edition. Sources range from Julius Caesar’s famous commentaries on his wars in Gaul to humble administrative tablets unearthed at Roman forts along Hadrian’s Wall. Memorial stones carved in the mysterious Ogham script, found from Cornwall to the west coast of Ireland, will also contribute their share of words.

The dictionary covers a sweeping period from around 325 BC to AD 500, the centuries when Celtic speech still dominated large parts of these islands. Almost everything we know comes second-hand. Celtic peoples themselves left hardly any writing of their own in the earliest centuries. Instead, Greek and Roman authors noted down tribal names, leaders, and settlements as they encountered them. Later, when Roman legions occupied Britain, soldiers and officials occasionally slipped a Celtic word into otherwise Latin documents. A weary centurion complaining about the weather, a merchant listing local goods, or a clerk recording a British recruit’s name might accidentally preserve a tiny piece of the old tongue for posterity.

Place-names have proved especially rich. The ancient name Moridunum, which means “sea fort” and survives in modern Carmarthen, reveals an early Celtic word for sea that closely matches môr in Welsh and muir in Old Irish. Such connections thrill the Aberystwyth team because they show how threads of the ancient language still run through the modern Celtic tongues of Wales, Ireland, Scotland, and Brittany. Cornish, recently revived after centuries of silence, also carries echoes of the same distant ancestor.

Dr Rodway explains that the project reaches far beyond pure linguistics. Historians will gain sharper insight into how Iron Age society was organised. Archaeologists will better understand the people who built hillforts and buried their dead beneath round barrows. Even archaeogeneticists, who study ancient DNA, may find the dictionary helpful when they try to match genetic patterns with the movement of languages across prehistoric Europe.

One of the biggest challenges lies in deciding what actually counts as ancient Celtic. Inscriptions in Celtic languages from Roman Britain are vanishingly rare, so the team must often work backwards from names preserved in Latin or Greek texts. They compare these with later evidence from medieval Welsh and Irish manuscripts to spot consistent patterns. Only then can they confidently claim a word belonged to the language spoken here two millennia ago.

Ireland presents a different puzzle. Because it lay beyond the Roman frontier, fewer written records survive from the early centuries. Yet Ogham stones, with their distinctive notches cut along the edges of standing stones, sometimes yield personal names or short phrases that match British material. Slowly but surely, the dictionary grows as each new fragment is checked, cross-referenced, and slotted into place.

The decision to produce both digital and printed versions reflects a desire to reach different audiences. Scholars around the world will be able to search the online database in seconds, while readers who simply love the feel of a book can hold the finished volume in their hands. Either way, the ancient Celtic dictionary will stand as a quiet monument to a language that refused to disappear entirely.

When the project reaches completion, probably several years from now, a remarkable chapter of British and Irish history will become clearer than ever before. We will hear, however faintly, the voices of people who looked out over the same hills and coasts we know today and gave them names that still whisper across the centuries.