1. a large tuna fish with dark blue coloring on its back and upper sides, highly valued for food

Examples

• The restaurant serves fresh bluefin sashimi.
• Commercial fishing of bluefin has been heavily regulated.
• A single bluefin can weigh over 600 pounds.
• The bluefin population has declined due to overfishing.
• Japanese buyers pay premium prices for quality bluefin.
• The bluefin migrates across the Atlantic Ocean.