GLEESON Family History
This is an anglicized form of the Olde Gaelic O' Glasain or O' Gliasain. The Gaelic prefix "O" indicates "male descendant of", plus the personal byname Glasain, from "glas" literally meaning "green", but used here in the sense of inexperienced. This sept belonged to the ancient territory of Mac Ui Bhriain Aradh's country, that is the area between Nenagh and Lough Derg on the border of North County Tipperary. The Gleesons were of the same stock as the O'Donegans, whose name derives from the Gaelic 'donn' meaning brown or dark.