All you need to know about the Celtic languages

All you need to know about the Celtic languages

by Leona Quigley

Updated November 10, 2022

Although the Celtic languages were once spoken across much of mainland Europe, today they are rarely spoken beyond the British Isles, Ireland and the French peninsula of Brittany. As a result there is a great deal of curiosity and confusion regarding these languages. As an Irish native I often get asked questions such as: is Celtic a language? Are Celtic languages spoken today? Do you speak Gaelic? 

Here we cast some light on the Celtic language origin, and give an outline of the six Celtic languages that are still in use and highlight their significance to the regions where they are spoken. It should be noted, however, that the Celtic languages, their cultural and political significance, and their complex history are all matters of intense debate.

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Historic roots of the Celtic Languages

The Celtic language family has its roots in the Bronze Age language of Proto-Celtic, which was widespread in central and Western Europe, from the Iberian peninsula perhaps even to the banks of the Black Sea. This now-extinct language was steadily replaced with Romance, Slavic and Germanic languages which spread north-eastwards across Europe with the movements of peoples. However, at some point prior to the fourth century BCE this predecessor to modern Celtic languages made its way across the English Channel to Great Britain and to the island of Ireland. 

Linguists have found evidence of a total of 16 Celtic languages to have existed. Yet whereas the Celtic languages that developed on continental Europe are all now extinct, the six that are still spoken today: Irish, Welsh, Breton, Scottish Gaelic, Cornish and Manx, all developed on the British Isles and in Ireland. 

These surviving languages fall into two subdivisions. The first language group are the Goidelic languages, or as they are more commonly known, Gaelic languages, Irish, Scots Gaelic and Manx. These are languages descended from the Old Irish tongue which developed on the island of Ireland. The second are the Brittonic (or Brythonic) languages, Welsh, Cornish and Breton, which as you might expect are descended from a language spoken across much of Great Britain prior to the spread of English across the island. 

While Brittonic and Gaelic languages are not mutually intelligible, there is some extent to which the languages within the Gaelic and Brittonic groups have shared elements. For instance, whereas an Irish speaker would struggle to understand someone speaking Scots Gaelic, they might well be able to guess the general drift of the conversation, particularly if they speak an Ulster (Northern Irish) dialect, but Welsh is completely unintelligible to Irish or Scots Gaelic speakers.

Goidelic (Gaelic) languages


Number of speakers: 170,000 native speakers and approximately 1.9 million speakers in total

Irish is a Gaelic language that developed on the island of Ireland but went into steep decline in the 17th to the 19th centuries, largely due to the harsh policies that repressed the language under English rule and exacerbated by the Great Famine of 1846-51. As Irish land was confiscated from native owners, English became the language of the ruling landlord class and when primary education was introduced, children were expected to learn and speak English and were punished for speaking their mother tongue.

Since the foundation of the independent state, Irish has been recognized as the first official language of the Republic of Ireland, though practically all government work is conducted through English in Ireland. There is a requirement of Irish language education that all Irish children learn Irish during primary and secondary school. 

Most native Irish speakers live in the Gaeltacht regions (special status language protected areas) along the Atlantic coast in the West of Ireland. However, fewer than 2% of the population actually use Irish daily outside of an educational context, therefore Irish is classified as an endangered language.

Scottish Gaelic

Number of speakers: 57,000 fluent speakers (native and second language speakers).  87 000 people claim to have some Gaelic language knowledge.

Following the migration of Old Irish speakers to the west coast of Scotland, Scottish Gaelic developed into a distinct language by the late Middle Ages. As you might notice from Gaelic place names that are ubiquitous in Scotland, most of the modern nation once spoke Scots Gaelic. Today, however, just over 1% of the modern Scottish population reports to be able to speak Scottish, most prominently in the Outer Hebrides. Strong revival efforts have long been underway, leading to a recent halt in the language’s decline.


Number of speakers: Approximately 2,200 on the Isle of Man

Manx or Manks, a Goidelic language which is also descended from Old Irish and was developed and spoken on the Isle of Man. Although the language is an important part of the small island’s cultural heritage, it went into stark decline from the 19th century due to the island’s economic dependence on Britain. Although Manx is rarely spoken as a first language today, having ceased to be used as a common means of day-to-day communication in the early twentieth century, there has nonetheless been a steady rise in the number of speakers over the last fifty years, making it a prominent example of a successful language revival effort.

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Brittonic languages


Number of speakers: Approximately 860,000 people in Wales

The most widely spoken Celtic language to have developed in Britain is Welsh. Its use began to decline as early as the later Middle Ages through a process of steady Anglicization that became systematized after the Act of Union incorporated Wales into the Kingdom of England in the 16th century. Although religious and educational movements managed to secure the survival of the language, the pressures of the British education system, the ubiquity of English amongst the upper classes, in the industrial centers and in mass media, the Welsh language went into sharp decline, especially in the twentieth century. However, a modern revival of interest in Welsh culture and literature has nonetheless shown potential to stem the decline of the Welsh language, with about 30% of Welsh citizens claiming to be able to speak Welsh as of 2021.


Number of speakers: Over 200,000 speakers in Brittany

Spoken in Brittany, France, Breton is the only Celtic language which is still in use on continental Europe, where it has been spoken since the 6th century when Celtic speakers fleeing from the Anglo-Saxon invasion of Britain settled on the French coast. It is most closely related to Cornish. 

Although Breton had over a million speakers in the mid-twentieth century, due to efforts by French authorities to repress the language, that number has fallen to less than a quarter of that today. Efforts to boost a revival have shown some signs of success, with more children receiving bilingual schooling year upon year. Nevertheless, the average age of speakers is 70 years old, which bodes poorly for the language’s future viability.


Number of speakers: 300-400 fluent speakers, 5000 with basic proficiency

In the southwestern English county of Cornwall, despite having been pushed westwards by Anglicization for centuries, the Cornish language is again spoken today. Although it ceased to be used as a day-to-day community language in the 18th century, it is now a revived language. A process of revival began in the early 1900s, as knowledge of the Cornish language had been passed down within families and preserved by individuals and scholars. There are a few hundred fluent speakers who are dedicated to the preservation of the language and some families have even begun to raise their children speaking Cornish as a first language.

Celts, culture and continuity

Although these languages have long been threatened by the dominant languages of their regions, the Celtic languages remain closely tied to the culture, traditions, music, dance and identities of those peoples who still speak and protect them. Not only that but they influence the way English is spoken in their regions, enriching the language with local quirks of phrase, proverbs and idioms. The passionate efforts of regional communities to preserve and foster new growth in their local tongue demonstrate the diversity inherent within larger national identities that might at first glance seem heterogeneous, and remind us all to appreciate the cultural value of each unique language

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Leona has her roots in the South of Ireland, where she grew up on her family farm. She went on to study World Politics at Leiden University College, The Hague and then completed her MPhil in International History at Trinity College Dublin. Leona has now settled in Berlin, having fallen in love with the city. In her spare time she is working on perfecting her German in anticipation of her doctoral studies, during which she plans to study modern German social history. Her hobbies include bouldering, dancing and reading a healthy mix of history books and corny fantasy fiction. You can find more info about her on LinkedIn.

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