Definition of eider in US English:


(also eider duck)


  • 1A northern sea duck, of which the male has mainly black and white plumage with a colored head, and the brown female has soft down feathers that are used to line the nest.

    Genus Somateria (and Polysticta), family Anatidae: four species, in particular the common eider (S. mollissima)

    • ‘Primary predators for these eiders were large gulls, and occasionally evidence of mammalian predation was found.’
    • ‘They frequently nest in colonies, often in association with eiders.’
    • ‘Both of these types are plentiful on the Cape, as are sea ducks, such as scoters and eiders, viewable from many vantage points.’
    • ‘Terns and eiders had been disturbed, while eiders had been doubly hit because the pickers were depleting the mussel beds on which they feed.’
    • ‘Sea ducks like scoters and eiders are also divers.’
    1. 1.1
      another term for eiderdown


Late 17th century: from Icelandic æthur, from Old Norse æthr.