Many place names in Ireland in the English language are either anglicisations of those in the Irish language, or completely different, such as the name for the capital of the Republic of Ireland, which in English is Dublin, but in Irish is Baile Átha Cliath. The former means black hole/pool (anglicised from dubh and linn) and the latter means town of the hurdle ford. After the foundation of the Irish Free State in 1922, some names were changed including Kingstown in County Dublin, which became Dún Laoghaire, and Queenstown in County Cork reverted to Cóbh. King's County and Queen's County were renamed County Laois and County Offaly in 1921.
The name of Ireland itself comes from the Irish name, Éire, affixed to the Germanic root, '-land'. According to mythology, Éire was an ancient Celtic princess. The four provinces are known as:
Connacht - Connacht(a)/Cúige Chonnacht - meaning "Conn's land"
Some common Irish place names:
Munster - An Mhumhain/Cúige Mumhan - meaning "Land of Mumha's men"
Leinster - Laighin/Cúige Laighean - meaning "Land of Broad Spears"
Ulster - Ulaidh/Cúige Uladh - meaning "Land of Ulaid's men"
Ard- ard - 'high'
Source: Wikipedia: Place Names in Irish
Ath- átha - 'ford'
Bally- baile - 'town'
Bel- béal - 'mouth'
Carry/Carrick- carraig - 'rock'
Clon- Cluain - a meadow
Dun- dún - 'fort'
Glas- glas - 'green'
Glen- Gleann - a valley
Kil- cill - church
Knock- cnoc - 'hill'
Rath- rath - 'fort'