Gaelic spoken in Ireland before English - Until 1800s Union is an English word. Uilleann is a Gaelic word.

Pipes developed in Ireland from a Pib Mor(Bag Pipe like the Scottish Pipes) to the Cuislean Pipes(Primitive Uilleann Pipes) in response to laws prohibiting the playing of the Pib Mor in Ireland. The English Government feared further union between the Irish and Scots. They said the Pib Mor was 'seditious' It was. (grins)

Pipes developed in secrecy - by the NATIVE Irish. over 300 years. Up till 1850s. These were very low volume and sweet powered by bellows not blow stem. They were pitched at C or below some as low as Bb.

If the people who invented the darn things called them Uilleann and they had to do it secretly for fear of the hangman then the name is good enough for me. :)