O%27riordan Family History
O%27riordan Name Meaning
Irish: Anglicized form of Gaelic Ó Ríoghbhárdáin ‘descendant of Ríoghbhárdán’ (see Riordan). This family is probably descended from Ríoghbhardán Ó Cearbhaill, who fell in battle in 1058.
Source: Dictionary of American Family Names ©2013, Oxford University Press