Heffernan, ó Ifearnáin A Gaelic surname meaning descendant of Ifearnán. A sept who were chiefs of Uaithne-Cliach, now the barony of Owneybeg in east Limerick. They were dispossessed by the O’Mulryans in the fourteenth century. In 1890 Heffernan was principally found in Tipperary, and the estimated number of bearers was 2,370. In the United States Heffernan is the 5,820th most numerous surname with an estimated 5,500 bearers.
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