Southeast is the direction halfway between south and east. Head southeast, the southeast corner, a southeast wind.
Southeast Asia is the standard name for the region from Myanmar to Indonesia, and it is capitalised where the plain direction is not. In gardening, a southeast aspect gets morning sun, which suits plants that dislike being scorched at midday.
1nounsoutheastThe direction halfway between south and east.
“Our holiday cottage is in the southeast, a short drive from the sea.”
southeast is a direction.
Old English suthest is simply south plus east, formed like all the intermediate compass points.
Old English
sūþēast
Middle English
southest
English, today
southeast
From Middle English southest, from Old English sūþēast, equivalent to south + east.
Etymology from Wiktionary, CC BY-SA