The 9 counties of the Province of Ulster.

Cavan
An Cabhán, `four lakes'
There is no trace of the original four lakes here now. They may have occurred where the rivers Burren and Barrow now meet.

	Donegal
	Dún na nGall, `fort of the foreigners'
	The `foreigners' were the Danes (Vikings) who took possession of a primitive fort here in the 10th century. The county took the name of the town.

Monaghan
Muineachán, `(place of) little thickets'
The town gave its name to the county. Monaghan is one of the three Ulster counties in the Irish Republic the others being Donegal and Cavan.

	Antrim
	Aontroim, `one house'
	The meaning is uncertain, but `solitary farm' is one possibility, from Irish aon, `one', `single' and treabh, `house', `family'. Another possible derivation is trom, genitive truim, `elder tree', although this seems less likely.

Derry
Doire, `oak grove'
There are many places in Ireland called `Derry' (Doire), and it soon becomes necessary to distinguish an individual name in some way, usually by adding a second word. In the case of Londonderry, the first distinguishing addition was Calgach, a personal name. This was recorded in the 7th century as Daire-Calgaich, 'Calgach's oak wood'. Meanwhile, St Columba had established a monastery here in the 6th century, and the name now became `Derry-Columcille' (Doire Choil Chille), `St Columba's oak wood'. Finally, `London' was added to Derry in 1609 when James I granted a charter for settlement here by merchants from London. Today the name is often used in its shorter original form of Derry. The original oak wood survived for several hundred years after the location was first settled. The county name (also often shortened) derives from that of the town.

	Down
	An Dún, `the fort'
	The fort concerned is Downpatrick, which gave its name to the county. Downpatrick is the site of Saint Patrick's grave.

Fermanagh
Fear Manach, `(place of the) men of Monach
This is a tribal name, referring to the leader, Monach. The tribe had to flee from their native Leinster after murdering the son of its king. Some settled in the country of Down, others settled by Lought Erne, where they gave their name to the territory (the present county).

	Tyrone
	Tír Eoghain, `Eoghan's land'
	According to historical legend, the territory here (much larger than the present county) was possessed by the descendants of Eoghan (Owen), son of Niall of the Nine Hostages.

From A Little Book of Irish Place Names by PW Joyce.