Eider

Chamber's Twientieth Century Dictionary · 1908 · p. 34

ī′dėr, n. the eider-duck, a northern sea-duck, sought after for its fine down.— n. Ei′der-down , the soft down of the eider-duck, used for stuffing quilts. [Prob. through Sw. from Ice. æðar , gen. of æðr , an eider-duck.]