1. An island in the northern Atlantic Ocean west of Great Britain, divided between the independent Republic of Ireland and Northern Ireland, which is a part of the United Kingdom. The island was invaded by Celts c. 500 BC and converted to Christianity by Saint Patrick in the fifth century AD. Ireland came under English control in the 17th century and was joined with Great Britain by the Act of Union in 1801. After the Easter Rebellion (1916) and a war of independence (1919-1921), the island was split into the Irish Free State (now the Republic of Ireland) and Northern Ireland, which is still part of the United Kingdom.
2. also Eir·e (ârə, īrə, ârē, īrē) A country occupying most of the island of Ireland. Organized as the semiautonomous Irish Free State by treaty with Great Britain in 1922, it officially became the sovereign state of Eire in 1937. Full independence came in 1949 when the Republic of Ireland was proclaimed, and the country withdrew from the Commonwealth. Dublin is the capital and the largest city.