Etymology From Middle English *southesterne, from Old English sūþēasterne, equivalent to south + eastern.
1
Of or pertaining to the southeast.
The southeastern part of the country is the most affluent.
Much of the southern half of the southeastern body is a mafic syenite, slightly more felsic than the shonkinite.1954, J. C. Olson, D. R. Shawe, L. C. Pray, W. N. Sharp, Rare-Earth Mineral Deposits of the Mountain Pass District, San Bernadino County, California, U.S. Geological Survey, Professional Paper 261, page 22:
1 more example
It’s the stuff of nightmares for some, but it’s simply summer in southeastern Colorado, where thousands – yes, thousands – of male tarantulas are making the trek to find a mate.2019 August 9, Dylan Miettinen, “Is that love in the air? Thousands of tarantulas to descend on southeast Colorado in search of mates”, in CNN: