The Collaborative International Dictionary of English v.0.48:
Southwestward \South`west"ward\, Southwestwardly \South`west"ward*ly\, adv. Toward the southwest. [1913 Webster] SouvenanceWordNet (r) 3.0 (2006):
southwestward adv 1: in a southwestward direction [syn: southwestward, southwestwardly] adj 1: toward the southwest n 1: the compass point midway between south and west; at 225 degrees [syn: southwest, sou'-west, southwestward, SW]