Or three nettle leaves vert.

The historic surname of O'Cleirigh derives from the Irish word "cléireach" meaning a clerk or cleric and is among the earliest of recorded hereditary names. The O'Cleary claim descent from Cleireach, who was of the same line of Guaire the Hospitable, King of Connacht. King Guaire gained this cogonomen during the 7th century, because he was the friend of priests and poets, and his palace is said to have once stood near the entrance to the town of Gort, from where he dispensed his hospitality to the local bards and scribes. "Thus in the hall of Gort spoke Guaire For the king let truth be told, Bounteous though he was, was weary Giving goblets, giving gold".

The Ó Cleirigh continued as one of the principal septs to reside in that part of South Galway which encompassed a good deal of the Diocese of Kilmacduagh.

In the 13th century, however, following Anglo-Norman conquests, they became dispersed and forced to settle in different parts of the country, but it was in County Donegal that they later achieved distinction as scribes and bards to the northern chieftains, O'Neills and O'Donnells.

Edward O'Reilly in his compendium of Irish writers cites no fewer than 10 bearers of the name who from the 16th to the 18th century made their mark on the poetic history of Ireland. An early aspirant, Goffrey O'Cleary left a number of poems on religious subjects still preserved on original parchment; one dwelt "with the respect Christians should have for Friday above other days of the week." Another associate who is named as Chief of the Clan put together some 100 verses in praise of St. Francis, founder of the Franciscan Order.

John O'Cleary treats of the long list of heroes and heroines who graced the pages of our annals and of the exploits of the fabled Macha Mongruadh, the only lady in Irish history to attain high chieftainship and who has a historic town called after her, namely - Ard Macha, Armagh, i.e., the Height of Macha.

1944 Postage Stamp in hounour of Brother Michael Ó Cléirigh

The best-remembered member of the clan, however, must be Michael Ó Cleirigh who, together with this brother Conaire and others, compiled that invaluable manual now known as "The Annals of the Four Masters". Following his entry to the Franciscan order in Louvain he was invited to return to Ireland to collect as much as possible and save from oblivion the historical records relating to Ireland. During his 10 year journey throughout the country he visited the libraries in both Ennis and Quin Abbeys, where much manuscript material was preserved. His labours resulted also in the compilation of an extensive list of the tribal kings of Ireland and with notes on the genealogies of the early Irish saints.

O'Reilly, Edward. "A chronological account of nearly four hundred Irish writers". Shannon, Irish University Press, 1970.
"Journal of the Society of Antiquaries of Ireland", vol. 34, Part 3 (1904).

Learned Families of Thomond