Definition of "southwest"
noun
usually uncountable, plural southwests
The intercardinal compass point halfway between south and west; specifically at a bearing of 225°.
Quotations
So this was my future home, I thought! […] Backed by towering hills, the but faintly discernible purple line of the French boundary off to the southwest, a sky of palest Gobelin flecked with fat, fleecy little clouds, it in truth looked a dear little city; the city of one's dreams.
1908, W[illiam] B[lair] M[orton] Ferguson, chapter IV, in Zollenstein, New York, N.Y.: D. Appleton & Company, page 40
adjective
not generally comparable, comparative more southwest, superlative most southwest
adverb
not generally comparable, comparative more southwest, superlative most southwest