nounpl. -·ders or -·der
- any of several large sea ducks (esp. genus Somateria) that live in northern regions of Europe, Asia, and North Americaoften eider duck
- eiderdown (sense )
Origin of eiderultimately from Old Norse æthar, gen of æthr, eider duck
Any of several large sea ducks, especially of the genus Somateria of northern regions, having soft, commercially valuable down and predominantly black and white plumage in the male.
Origin of eiderBack-formation from eiderdown
male (foreground) and female (background) common