1. Someone who is from Ireland. the Irish have been given many stereotypes (both positive and negative)
2. some American who thinks it's cool to be Irish and so proclaims that they are indeed "Irish" because their great great grandfather may or may not have come from Ireland. see Poser.
Irishman: "i am from Ireland, thus i am IRISH"
Poser: "my Great, great Grandfather's cousin once met an Irishman, thus i am Irish"