Treacy, Tracey, Tracy, ó Treasaigh A Gaelic surname derived from Treasach meaning ‘warlike, fierce’. A sept of Leinster who were anciently lords of Ui Bairrche a district embracing the Barony of Slievemargy in Laois. A sept of Connacht of the same stock as the Madden’s who were seated in south-east Galway. A sept of Fermanagh. In 1890 Treacy was principally found in Tipperary and Galway, Tracet and Tracy in Dublin, and the estimated number of bearers was 3,765 (all variants). In the United States Tracy is the 1,082nd most numerous surname with an estimated 30,200 bearers, and Tracey is the 4,790th most numerous surname with an estimated 5,500 bearers.