What is "common goldeneye"

n. A medium sized sea duck, ''Bucephala clangula''.

The common goldeneye (Bucephala clangula) is a medium-sized sea duck of the genus Bucephala, the goldeneyes. Its closest relative is the similar Barrow's goldeneye. The genus name is derived from Ancient Greek boukephalos, "bullheaded", from bous, "bull " and kephale, "head", a reference to the bulbous head shape of the bufflehead. The species name is derived from Latin clangere, "to resound".