Your answer is informative, helpful, and non-judgmental. I hate it and I hate you, too.

Depends on your perspective? “Erin” is an Anglicized version of “Eirinn”, which is one of the forms in Gaelic for “Eire” = i.e., Ireland. “Eireann” is the genitive, like “of Ireland,” so the Dail Eireann is, literally, “Assembly of Ireland” (one of the houses of their legislature).