According to Great British Chefs, cod loin refers to the middle portion of the meat after a cod has been filleted. It is normally short and fat compared to the rest of the fish and is generally considered a prime cut.
Cod loin is often sold boneless and skinless, but it is possible to buy it with the skin. It is ordinarily sold frozen but can also be found fresh.
The meat from cod loin is rather sturdy for a white fish, which makes it ideal for baking, using in stews or in a bouillabaisse. It can also be battered, pan-fried, poached or steamed.