The Collaborative International Dictionary of English v.0.48:

Southeast \South`east"\ (?; by sailors sou"-), n.
   The point of the compass equally distant from the south and
   the east; the southeast part or region.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Southeast \South`east\ (?; by sailors sou"-), a.
   Of or pertaining to the southeast; proceeding toward, or
   coming from, the southeast; as, a southeast course; a
   southeast wind.
   [1913 Webster]

WordNet (r) 3.0 (2006):

southeast
    adv 1: to, toward, or in the southeast [syn: southeast,
           south-east, sou'-east]
    adj 1: coming from the southeast; "southeasterly breezes" [syn:
           southeasterly, southeast]
    2: situated in or oriented toward the southeast [syn:
       southeast, southeastern, southeasterly]
    n 1: the compass point midway between south and east; at 135
         degrees [syn: southeast, sou'-east, southeastward,
         SE]
    2: the southeastern region of the United States [syn:
       Southeast, southeastern United States]
    3: the direction corresponding to the southeastward compass
       point
    4: a location in the southeastern part of a country, region, or
       city