- 1
A thick, warm cover you put on a bed, filled with very soft feathers. Those feathers are down — the fluffy layer under a bird's outer feathers, not the opposite of up. The first part is eider, a sea duck whose breast down is unusually light and warm, so a true eiderdown was once a rather special, expensive thing. Though actually, in everyday British English people often say eiderdown for any thick feather quilt, even when the filling is ordinary duck or goose down, or a mix. Older speakers in Britain use it a lot for the heavy cover that sits on top of the sheets; younger people more often say duvet. It sounds and a little old-fashioned, not like a shop label. You would not use it for a thin blanket or for a winter coat.
羽絨被（英國口語也常泛指厚被子，不一定真是絨鴨毛）
原始詞典資料2 筆記錄
以下是外部詞典記錄的用法，原文照列，我們還沒有寫成教學內容。上面的說明才是我們自己寫的；有些用法可能上面已經講過了。
eiderdownnoun
- 1
The down of the eider duck, used for stuffing pillows and quilts.
- A great sea lifted us high and, crashing down with a deafening roar, carried us swiftly along on light foam as soft as eiderdown.
- 2
A quilt stuffed with this down.
- The landlord was near spraining his wrist, and I told him for heaven’s sake to quit—the bed was soft enough to suit me, and I did not know how all the planing in the world could make eider down of a pine plank.
- I entered. It was a very small room, overcrowded with furniture of the style which the French know as Louis Philippe. There was a large wooden bedstead on which was a billowing red eiderdown, and there was a large wardrobe, a round table, a very small washstand, and two stuffed chairs covered with red rep.
資料來源：英文維基詞典 English Wiktionary（CC BY-SA 4.0）。 原文照列，未經改寫。