Ó Cléireacháin
Ó CLÉIREACHÁIN, Ó CLÉIRCHÍN—I—O Clearkane, O Clercan, Clerihan, Clerkan, Clerkin, Clarkins, Clarke, &c.; 'descendant of Cléireachán,' or 'Cléirchín' (diminutive of cléireach, cleric, clerk); the name (1) of a family of Ui Fidhgheinte who were anciently lords of Ui Cairbre Aebhdha, in the east of Co. Limerick; now represented by Clerihan in Co. Tipperary; and (2) of a Meath family who were anciently lords of Coillte Fallamhain. This family probably removed to Monaghan and Cavan, where the name was common at the end of the 16th century.
Alphabetical Index to Irish Surnames