The Collaborative International Dictionary of English v.0.48:

Southwest \South`west\ (?; colloq. sou"-.), n.
   The point of the compass equally from the south and the west;
   the southwest part or region.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Southwest \South`west"\, a.
   Pertaining to, or in the direction of, the southwest;
   proceeding toward the southwest; coming from the southwest;
   as, a southwest wind.
   [1913 Webster]

WordNet (r) 3.0 (2006):

south-west
    adv 1: to, toward, or in the southwest [syn: southwest,
           south-west, sou'west]