south·west·er·ly I. \-tərlē, -li, -R -təl- sometimes -təl-\adverb (or adjective) Etymology: from southwest (II), after English west : westerly 1.: from the southwest < a southwesterly weather pattern > 2.: toward the southwest < this part of US 277 extends southwesterly, then south — American Guide Series: Texas > II. noun : a wind from the southwest