Collocations for retailer - noun

big, giant, large
leading, major, top
the country's biggest food retailer

small
local
high-street (BrE)
High-street retailers reported a marked increase in sales before Christmas.

big-box (= that sells large items)
mass (AmE), mass-market
multiple
independent
niche (esp. BrE), specialist (BrE), specialty (AmE)
high-end (AmE), luxury (esp. AmE), upscale (AmE)
discount
brick-and-mortar (AmE), bricks-and-mortar (AmE), traditional
Internet, online, Web
apparel (AmE), clothing, DIY (BrE), electrical (BrE), electronics, fashion, food, furniture, grocery, music, toy, etc.