Combination of dorm and asshole. Quite simply, a college student who is a real asshole that lives with other people in a dorm. Most likely an immature underclassman, a dormhole demonstrates a noticeable lack of courtesy and personal hygiene.
I half-slept through an entire night before an exam listening to dormholes talk loudly in the hallways and slam their doors when going in and out of their rooms. Moreover, they got drunk, trashed the main lounge, and shit on floor.