Ap·pa·la·chian Mountains /ˌæpəˈleʧ(i)ən, ʃ(i)ən; ˈlæʧ(i)ən/
  Appalachian Mountains
       n : a mountain range in the eastern United States extending from
           Quebec to the Gulf of Mexico; a historic barrier to early
           westward expansion of the United States [syn: Appalachians]