A small stiff-tailed duck, Oxyura leucocephala, of Asia, North Africa, and (rarely) Spain, the male of which has a predominantly white head and a blue bill.
Origin
Late 18th century; earliest use found in John Latham (1740–1837), naturalist.
Definition of white-headed duck in US English:
white-headed duck
noun
A small stiff-tailed duck, Oxyura leucocephala, of Asia, North Africa, and (rarely) Spain, the male of which has a predominantly white head and a blue bill.
Origin
Late 18th century; earliest use found in John Latham (1740–1837), naturalist.