The name Brady in Ireland is derived from the Irish name Mac Bradaigh meaning 'spirited'. Although the anglicised form should therefore be MacBrady, the prefix Mac has seldom if ever been used in modern times. The modern use of the prefix O instead of Mac with this name is erroneous. This Sept was based in County Cavan.
From an Irish surname which was derived from Ó Brádaigh meaning "descendent of Brádach". The personal name Brádach probably derives from a Gaelic word meaning "large-chested".