The Collaborative International Dictionary of English v.0.48:
Southern \South"ern\ (?; 277), a. [AS. s[=u][eth]ern. See
Of or pertaining to the south; situated in, or proceeding
from, the south; situated or proceeding toward the south.
Southern Cross (Astron.), a constellation of the southern
hemisphere containing several bright stars so related in
position as to resemble a cross.
Southern Fish (Astron.), a constelation of the southern
hemisphere (Piscis Australis) containing the bright star
Southern States (U.S. Hist. & Geog.), the States of the
American Union lying south of Pennsylvania and the Ohio
River, with Arkansas, Louisiana, and Texas. Before the
Civil War, Missouri also, being a slave State, was classed
as one of the Southern States.