The term EIDER is a type of DUCK that is found in the northern hemisphere. It is also known as the Common Eider and is the largest species of sea DUCK. The scientific name for this species is Somateria mollissima. The crossword solutions for this term are DUCK (4 letters) and DOWN (4 letters). The term DUCK is an obvious reference to the species, while DOWN is a reference to the bird's soft feathers which are used to make DOWN jackets and other items of clothing.