Erin is a personal name taken from the Hiberno-English word for Ireland, originating from the Irish word "Éirinn". "Éirinn" is the dative case of the Irish word for Ireland, "Éire", genitive "Éireann", the dative being used in prepositional phrases such as "go hÉirinn" "to Ireland", "in Éirinn" "in Ireland", "ó Éirinn" "from Ireland".

The dative has replaced the nominative in a few regional Irish dialects (particularly Galway-Connemara and Waterford).^[1] Poets and nineteenth-century Irish nationalists used Erin in English as a romantic name for Ireland.^[2] Often, "Erin's Isle" was used. In this context, along with Hibernia, Erin is the name given to the female personification of Ireland, but the name was rarely used as a given name, probably because no saints, queens, or literary figures were ever called Erin.^[3]

According to Irish mythology and folklore, the name was originally given to the island by the Milesians after the goddess Ériu.

The phrase Erin go bragh ("Éire go brách" in standard orthography, dative "in Éirinn go brách" "in Ireland forever"), a slogan associated with the United Irishmen Rebellion of 1798, is often translated as "Ireland forever".^[4] The songs 'Let Erin Remember' and 'Érin grá mo chroí' are more examples of the word's usage in Irish romantic nationalism.^[5][6]

As a given name, Erin is used for both sexes, although, given its origins, it is principally used as a feminine forename. It first became a popular given name in the United States.^[3] Its US popularity for males peaked in 1974 with 321 boys registered with the name.^[7] Erin is also a name for Ireland in Welsh, and is one of the 20 most popular girls' names in Wales.^{[8] [9]}

As a family name, Erin has been used as one of the many spellings of the name of the Scottish clan "Irwin"—which was involved in the Scottish Plantations of Ireland.^[10] However, that name was originally derived from the place of the same name near Dumfries, and means "green water", from Brittonic ir afon.^[11][12]