Celtic languages scholar who specialised in the Irish dialects of Ulster

Cathal Ó Dochartaigh, who has died aged 72, was emeritus professor of Celtic at the University of Glasgow.

Cathair Niall Ó Dochartaigh, known to friends and colleagues as Cathal, was born in Derry in 1942 but his family moved to Belfast when he was three.

After secondary education at St Malachy's College he went to Queen's University, where he studied under the Swiss linguist Heinrich Wagner, graduating with a BA in Celtic Studies in 1965. He learned Scottish Gaelic and Welsh, spending four months on South Uist, Barra and Eriskay, where he collected folklore and dialect material, and several months in Aberystwyth. He gained qualifications in general linguistics (1966) and phonetics (1967) at the University of Edinburgh and was employed there as assistant lecturer with the Linguistic Survey of Scotland (1966-69). In 1972 he completed a postgraduate MA thesis at Queen's University Belfast on the phonology of Ros Guill Irish.

He met his future wife, Jane (née Sykes), in 1969 in Edinburgh University library, where she then worked. They married in 1971.

In 1969 he had been appointed to a lectureship in Celtic in the University of Aberdeen. Hens, geese and ducks The family moved to the Esslemont Station House, near Ellon, in 1974, to what was to become a memorable homestead, where he grew vegetables and kept hens, geese and ducks. Ten years later he was awarded a PhD by the University of Aberdeen on the basis of his doctoral thesis on “Dialect Differentiation in the Irish of Ulster”.

In 1982 he become director of the Linguistics Institute of Ireland in Dublin, before moving to Bangor, North Wales, in 1984 as a freelance academic computer and Celtic languages consultant. He worked on a Welsh language spellchecker and a computerised dictionary at the University of North Wales, and was involved in producing a digitised version of Ó Dónaill's Irish-English Dictionary.

He worked on the five volumes of the Survey of the Gaelic Dialects of Scotland (1994-97), one of the monumental achievements in Celtic linguistics in the 20th century. He also provided the earliest empirical cross-sectional study of intergenerational sound change in Irish in his analysis of Rann na Feirste speakers, marking him as one of the pioneers of Irish sociolinguistics.

One of the hallmarks of his work was his theoretical approach to the Gaelic languages, culminating in his impressive Dialects of Ulster Irish (1987).

He was appointed to the chair of Celtic at the University of Glasgow in 1996, a position he occupied until his early retirement in 2004. From 2002 he had begun to show early signs of what was in 2005 diagnosed as dementia. Voracious mind Cathal Ó Dochartaigh was an academic and deep thinker whose voracious mind delighted in culture, sociology and politics as well as language and literature.

He was fluent in Irish and Welsh, and also learned some French, German, Swedish, Portuguese and Russian.

He could be irreverent and was full of mischievous fun. Once people got to know him, he earned the lifelong trust and loyalty of colleagues and students alike.

Averse to hierarchies, he treated everyone alike. He was kind and generous to family and friends, and especially supportive of students and early career academics.

After his dementia diagnosis his wife cared for him for over two years until he became too ill and he moved to a care home in Glasgow, where staff looked after him lovingly and treated him with the dignity he deserved.

He is survived by his widow, Jane, his children, Brighid, Domhnall and Ruairí, and his grandchildren, Evan and Lucy. Suaimhneas síoraí go raibh aige.