a) anybody who was born in America, is white and has a last name like Smith, Johnson or Washington;
b) anybody who talks or acts like somebody covered under definition A;
c) the opposite of an Italian-American;
d) a Wonder Bread Wop.
etym. Italian 'americano'
Maria: Honey, how was lunch yesterday at the Johnson's?
Vinnie: Maronn'! Those merigans couldn't prepare a TV dinner even if they tried!