Erin was the ancient Gaelic name of Ireland, given to the land by the Milesians (according to Irish mythology and folklore) after the goddess Ériu. Nineteenth century Irish nationalists used 'Erin' as an anglicised Gaelic name for Ireland, as shown in the catchphrase when speaking of Ireland's experiences with Britain, "Let Erin Remember".

The modern Irish name of the country is Éire; the genitive case is Éireann and the dative is Éirinn.