Anglicized form of Irish Éirinn. Erin has been used as a poetic name for Ireland for centuries, and in recent years this has become a popular given name in the English-speaking world, even among people with no Irish connections.
Irish: Anglicized form of Gaelic Ó Briain ‘descendant of Brian’, a personal name probably based on the element bre- ‘hill’, with the transferred sense ‘eminence’, i.e. ‘exalted one’. See also Bryan. In Ireland there has also been some confusion with O’Byrne (see Byrne).