south·east·er·ly I. \-tərlē, -li, -R -təl- sometimes -təl-\adverb (or adjective) Etymology:south (II) + easterly, adverb or adjective 1.: from the southeast < southeasterly gale > 2.: toward the southeast < held a southeasterly course > II. noun Etymology:south (II) + easterly, n. : a wind from the southeast < it doesn't take one of those southeasterlies long to come up — Norman Lewis >