Sheridan, ó Sirideáin A Gaelic surname meaning descendant of Sirideán. A sept of Longford who were erenaghs of Granard, who afterwards moved to Cavan. A sept of the Síol Muireadhaigh in Connacht. In 1890 Sheridan was numerous in Cavan and Sligo, it was also to be found in Dublin and Mayo. The estimated number of bearers was 6,496 (including variants). In the United States it is the 1,572 most numerous surname with an estimated 22,000 bearers.