situated in or oriented toward the southeast
"The new highway runs directly to the southeastern part of the city, where the rivers meet the coast."
of a region of the United States generally including Alabama; Georgia; Florida; Tennessee; South Carolina; North Carolina
"The southeastern states, which include Alabama and Georgia, are known for their humid summers."
Of or pertaining to the southeast.
"The southeastern corner of the state is known for its humid summers and mild winters."
In plain English: Southeastern means located toward both south and east on a map.
"The wind blew strongly from the southeastern direction today."
Southeastern comes from the Middle English word southesterne, which was formed by combining "south" and "eastern." This term has retained its original meaning of describing a direction located between the south and east.