Linguists at Aberystwyth University have launched the first comprehensive dictionary to capture every known word of the Celtic languages spoken in Britain and Ireland between 325 BC and AD 500. The three-year project, funded by the Leverhulme Trust, will gather more than 1,000 ancient Celtic terms from scattered inscriptions, Roman records and early medieval manuscripts.
As Dr. Simon Rodway, the project's lead, puts it:
“These disparate sources have never before been brought together in a way that offers such an insight into the nature of Celtic languages spoken in these islands at the dawn of the historical period. The picture of the linguistic landscape of Britain and Ireland will be of interest not only to linguists but to historians, archaeologists and archaeogeneticists.”
For scholars and enthusiasts alike, this dictionary isn't just a lexicon - it's a bridge to the past, illuminating how ancient Celts thought, traded, and told their stories.
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Dr. Simon Rodway of Aberystwyth University with a book. (Aberystwyth University)
£300,000 Grant Funds Landmark Study
The £300,000 research grant will support a small team at Aberystwyth’s Department of Welsh and Celtic Studies as they trawl through centuries-old sources. These include around 400 surviving Ogham stones – mostly from Ireland and south-west Wales – plus Celtic personal names, tribal names and place names recorded by Greek and Roman writers.
“Until now, scholars have studied these fragments in isolation,” Dr Rodway told reporters. “By combining every scrap of evidence we can finally see patterns in vocabulary, grammar and sound changes that have never been visible before.”
The Roots of a Lost Legacy
The Celtic languages once echoed across vast swaths of Europe, from the hills of Ireland to the rugged coasts of Gaul. Emerging around 1200 BC from the Proto-Indo-European family, they splintered into branches like Goidelic (ancestors of Irish and Scottish Gaelic) and Brythonic (roots of Welsh and Cornish). Yet, by the Roman era, direct evidence dwindled - Celts favored oral traditions over writing, leaving behind only fragments in inscriptions, place names, and borrowed words in Latin texts. This scarcity has long frustrated linguists, who rely on indirect clues like Julius Caesar's accounts of Gallic tribes or Greek chroniclers' notes on Celtic mercenaries. The new dictionary tackles this head-on, drawing from sources dated 325 BC to AD 500, a pivotal window when Celtic speech mingled with invading forces. As Rodway notes in a recent interview with The Guardian:
"We're dependent on documents that are written either in Latin or Greek, but which contain names of places, ethnic groups or individuals that we can say are Celtic."
This compilation promises to trace evolutions, such as the shared root for "sea" - môr in Welsh, muir in Old Irish - echoing in ancient place names like Moridunum, or modern Carmarthen.
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Unearthing Words from Stone and Scroll
At the heart of this linguistic quest lies a treasure trove of inscriptions, particularly those in Ogham, the cryptic script of straight lines notched into edges of stones, bones, or wood. Invented around the 4th century AD, Ogham served as Ireland's earliest writing system, often marking memorials or boundaries with Primitive Irish phrases like "MAQI MUCOI" (son of the tribe).
The dictionary will weave in over 400 known Ogham stones - 360 from Ireland alone - alongside Roman-era finds from Britain, where Celtic words slipped into soldiers' letters and administrative ledgers. Less material survives from Ireland, untouched by Roman rule, but gems like the Ratass stone in Kerry blend Ogham with Latin crosses, hinting at early Christian influences.
The ogham stone at Ratass in County Kerry, Ireland. (Kierandoc/CC BY-SA 4.0)
Rodway's team, funded by a three-year Leverhulme Trust grant, sifts through these relics, cross-referencing with continental evidence like Gaulish tablets. Challenges abound: erosion claims stones yearly, and interpretations vary, but digital 3D scanning offers hope. "People have studied placenames before and a few inscriptions but we're going to try and get everything together and see what patterns emerge," Rodway explained.
Beyond vocabulary, patterns may reveal trade routes or migrations, enriching our grasp of Celtic inscriptions.
This project builds on prior efforts, like the OG(H)AM database, which catalogs inscriptions digitally. Yet, it stands apart by integrating Old Irish with ancient British Celtic, potentially debunking fanciful theories on pre-Celtic tongues. As one expert reflected, "A full collection of the available evidence will allow us to sort the wheat from the chaff." For Ireland, where Ogham dots the landscape from Dingle to Donegal, this means reclaiming voices long silenced.
Bridging Eras: From Ancient Echoes to Modern Tongues
What makes this dictionary transformative is its gaze toward the present. Modern Celtic languages—Irish, Welsh, Scottish Gaelic, Breton, Cornish, Manx—carry ancient DNA, with about a million speakers worldwide. Words like "muir" persist, linking today's bilingual signs in Galway to Caesar's Gallic wars. The project evaluates how early Celtic evolved amid invasions, from Viking raids to Norman conquests, and even probes non-Celtic substrates in prehistoric Britain.
Rodway emphasizes its interdisciplinary pull:
"The picture of the linguistic landscape of Britain and Ireland will be of interest not only to linguists but to historians, archaeologists and archaeogeneticists."
Imagine archaeologists cross-checking DNA from Celtic graves against linguistic migrations, or educators using the dictionary to revive fading dialects in Welsh schools.
Printed and online versions will democratize access, fostering apps for Ogham translation or virtual tours of inscription sites. In a world racing toward monolingualism, this work honors resilience - Celtic tongues endured where Latin faltered. As Rodway shared, "It's extremely exciting to lead this project and pen the first dictionary of this kind." It reminds us that language isn't mere words; it's the thread weaving identity, myth, and memory. For those tracing Celtic myths, this lexicon unlocks doors to bards' tales and druids' chants, proving ancient Celtic isn't lost it's waiting to be spoken anew.
Top image: Ogham inscriptions on ancient stones from Ireland and Cornwall. Source: Handout/ The Guardian
By Gary Manners
References
Sheils, C., 2025. New dictionary to shed light on Ireland’s earliest Celtic language. Available at: https://www.irishnews.com/news/northern-ireland/new-dictionary-to-shed-light-on-irelands-earliest-celtic-language-SJJZN2VIDFGIHMYMY5DHKBBEHQ/
Morris, S., 2025. Linguists start compiling first ever complete dictionary of ancient Celtic. Available at: https://www.theguardian.com/science/2025/dec/08/linguists-start-compiling-first-ever-complete-dictionary-of-ancient-celtic
