Wiktionary
n. (context colloquial idiomatic English) A house with no internal barrier between the front and back doors.
Usage examples of "shotgun shack".
He found the address: A shotgun shack/dingy/three small rooms tops.
A small shotgun shack of unpainted wood sat just beyond it, which also leaned to one side, as though it had become too much of an effort to remain vertical.
It had suffered from the immersion in the river, and he had worked on it for hours in Paddy Maxwell's shotgun shack, polishing and wiping away the flowers of rust that marred the oily sheen of the eighteen-inch steel blade.
He's locked himself in there and there's no other way out of this shotgun shack.
It was a sodbuster's shotgun shack, with a single hallway and the rooms opening off to one side, a small parlor, then a bedroom with bunks, and finally a tiny kitchen with an iron stove and hand-pumped sink.