Hi Helen, We can refer to "southeastern" as an adjective to describe a portion of the country (noun). Alabama is a southeastern state in the US. However, you can also use "southeast" as a noun to describe a part of the country itself. Alabama is in the southeast of the US. / Alabama is in the southeast. Southeastern is an adjective and must be paired it nouns like "region, corner, state, province etc". Hope this helps. Cheers, Lance