1. The soft, fluffy down feathers from the breast of an eider duck, used as filling for quilts, pillows, and jackets.
2. A quilt or comforter filled with eiderdown feathers.
Usage: chiefly British

Examples

• The jacket was filled with eiderdown to keep her warm in the Arctic cold.
• She snuggled under the eiderdown on the cold winter night.
• Eiderdown is prized for its exceptional insulating properties and lightweight feel.
• The pillows were stuffed with genuine eiderdown, making them incredibly soft.
• Eiderdown quilts are expensive but last for many years with proper care.
• The comforter's eiderdown filling made it perfect for mountain camping trips.