southeast has 7 distinct synonyms spread across 5 of its 7 senses. Each sense below keeps its own list, because a synonym belongs to a meaning and not to a word: swapping one sense's substitute into another sense's sentence is how a thesaurus makes writing worse. WordNet records no antonym for it — antonymy is a relation between word forms rather than concepts, so it is deliberately sparse.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
the compass point midway between south and east; at 135 degrees
the southeastern region of the United States
the direction corresponding to the southeastward compass point
a location in the southeastern part of a country, region, or city
situated in or oriented toward the southeast
to, toward, or in the southeast
Synonyms, antonyms and the broader and narrower relations for southeast come from Princeton University’s WordNet. Full sources and licences.