Gray Market
  
You’ve heard of a black market. It’s the term for underground commerce, trade in illegal items...things like heroin or rocket launchers.
On the other end of the spectrum, you have normal, legal markets. Buying paper towels from Amazon, going grocery shopping, or stopping at Walmart to buy a dozen socks for $3.99. The sellers and buyers in this market follow all regulations and pay all required taxes. Everything is above board.
In between the black market and totally legal commerce exists a gray market. It’s not the sort of illicit trade that will get you thrown in the slammer, but it’s not completely legit either. These might be overseas products that have skirted import duties, or items that violate trademark restrictions, or shady secondary markets (that booth at the back of the flea market with the suspiciously good prices on perfume and Blue-rays).