Wiktionary
big box
n. A large self-service store, usually on a single level, with few interior walls, owned and run by a corporation
Wikipedia
Big Box
Usage examples of "big box".
Orabona and I went to the Surface for the big box, but when we had packed it we couldn't get It up the three flights of steps.
Orabona and I went to the surface for the big box, but when we had packed it we couldn't get It up the three flights of steps.