de Bhaldraithe, Tomás (1916–96), Irish-language scholar, was born in Ballincurra, Co. Limerick, one of five children of Pádraig de Bhaldraithe (1884–1953), civil servant, from Nenagh, Co. Tipperary, and Eilís Nic Conmara (1886–1973) from near Kilkee, Co. Clare. When his family moved to Donnybrook, Dublin, he was enrolled in Muckross Park school (1923). His father was an Irish language enthusiast, and Tomás's own interest in things Irish is evidenced by his successful attempt to introduce the sport of hurling to the solidly rugby-playing Belvedere College (which he attended 1926–34), and later by his attendance at Coláiste Eoghain Uí Chomhraí, Carraig an Chabhaltaigh, Co. Clare, in the summers of 1931–2. He first travelled to the Gaeltacht in 1933, attending courses in Cois Fharraige, Co. Galway, and thus beginning an attachment to Connemara that lasted until his death. His outstanding academic career began in 1934 with an entrance scholarship to UCD. He graduated BA (1937) with first-class honours in French, Irish, and English. In 1938, on an NUI travelling studentship, he went to study at the École Pratique des Hautes Études in Paris, attending courses in Celtic studies, medieval Latin, and general linguistics (among other subjects). Returning to Dublin in 1939 when his Paris studies were cut short by the outbreak of war, he received an MA from UCD for a thesis entitled ‘Bunús na haislinge’, and obtained special permission to use the remainder of his travelling studentship to conduct intensive research into the Irish of Cois Fharraige (1939–41). The results of this work were later published as the seminal The Irish of Cois Fhairrge, Co. Galway: a phonetic study (1945) and Gaeilge Chois Fhairrge: an deilbhíocht (1953). He lodged in the Diolún house in Baile an Tí Mhóir during these years, collecting samples of language usage by day and writing them up at night by candlelight. His trusty bicycle gave further service to Irish when, after his departure from Connemara, it became the warhorse of the celebrated folklore collector Calum Mac Gill-Eain. On his return to Dublin, he enrolled in a course in phonetics given by Eileen Evans at the Dublin Institute for Advanced Studies (DIAS), lasting until summer 1941; once more the war impinged on his studies when Evans, who worked at the University of London, was enlisted to help in the British war effort and could not resume teaching in Dublin in the autumn. De Bhaldraithe received his Ph.D. from the NUI (1942) for a thesis based on his work in Cois Fharraige. After spending a further year as a scholar in the DIAS, he became an assistant in the department of modern Irish in UCD (1943) and rose quickly through the ranks, becoming an assistant lecturer (1946) and statutory lecturer (1952), and holding the chair of modern Irish language and literature 1960–78. From 1978 till his retirement from UCD (1986), he was professor of Irish dialectology, a post specially created for him. He founded the archive of Irish dialects in the Irish department in 1956 (and ran it till 1986), and set up the college's language laboratory. In addition, he was dean of the faculty of Celtic studies (1971–6) and a member of the university's governing body (1973–9). He was equally active outside the university: he became a member of the RIA (1952) and its vice-president (1965–6, 1981–3); served on the board of the school of Celtic studies, DIAS (1961–95), and as its chairman (1985–95); was appointed (1958) to the placenames commission, which he chaired (1981–96); and felt especially honoured to be made patron of Conradh na Gaeilge's Oireachtas (1991).
He will be chiefly remembered as a lexicographer, particularly for his English–Irish dictionary (1959; additions and corrections, 1978), undoubtedly one of the most significant contributions ever made towards building up a language infrastructure for speakers, writers, and learners of Irish. Although this work has since been criticised as being out of date – by himself among others – it has stood the test of time, and blame for the failure to update it further does not rest on its author's shoulders. He will also be remembered for his six years grudgingly acknowledged work as advisory editor on Niall Ó Dónaill's Irish–English dictionary (1977); for his role (1976–95) as general editor of the RIA's unfinished monolingual historical dictionary of modern Irish; and for founding and contributing to the RIA's valuable Deascán foclóireachta series of word collections from the living language of the Gaeltacht as part of the dictionary project. As well as his work on Irish language lexicography, he acted as a consultant on words of Irish and Hiberno-English origin for the New shorter English dictionary (Oxford), and for Collins’ English dictionary. He also made a foray into broadcasting as host of RTÉ's successful Fadhbanna Gaeilge programme. Always committed to Irish as a living language, he was instrumental in the early 1940s in the founding of An Comhchaidreamh (an organisation intended to foster cooperation between the Irish-language societies of third-level colleges) and its long-lived monthly publication Comhar. The fact that, unusually for Irish-language academics, Irish was always his preferred language of discourse is further proof of this commitment. He did not, however, confine himself to linguistics or the fortunes of the language itself, and his interest in Irish writing is shown by the editions he produced of contemporary short stories (Nuascéalaíocht, 1952), of the stories of Pádraic Ó Conaire (qv) (Scothscéalta, 1956; Seacht mbua an éirí amach, 1967), of the diaries of Amhlaoibh Ó Súilleabháin (qv) (1970), and of Seanchas Thomáis Laighléis (1977). A complete bibliography of his academic work, numbering more than a hundred articles as well as several books, is to be found in Cuimhní cairde. The caricature adorning the front cover of that book depicts him as a latter-day version of the monk in the poem ‘Mise agus Pangur Bán’, who compares his cat's delight at catching mice with his own delight at catching words; the caption, a line from that poem, ‘do thabhairt doraid go glé’ (to make what is unclear clear) is particularly appropriate for a man who, despite his great learning, always described himself as ‘ag foghlaim Gaeilge’ (learning Irish). It also seems appropriate that this humble diligent scholar should die (in Dublin, 24 April 1996) after launching a collection of a friend's writings entitled The words we use. He married (1943) Vivienne Ní Thoirdhealbhaigh; they had nine children.