The Collaborative International Dictionary
Aythya vallisneria
Canvasback \Can"vas*back`\, n. (Zo["o]l.) A Species of duck ( Aythya vallisneria), esteemed for the delicacy of its flesh. It visits the United States in autumn; particularly Chesapeake Bay and adjoining waters; -- so named from the markings of the plumage on its back.