megastore; superstore
Refers to an exceptionally large retail store, often a big-box store or hypermarket, emphasizing scale beyond a typical large store.
A new megastore opened in the suburbs.
The product range of a superstore overwhelms that of small and medium-sized shops.
大型店 is a general term for a large store, while 超大型店 emphasizes an even larger scale, often used for massive retail outlets.
Compound of 超 (chō, 'super-', 'ultra-') + 大型 (ōgata, 'large-scale') + 店 (ten, 'store'). A straightforward modern coinage for very large retail establishments.