1. grayback(n = noun.animal) greyback, limnodromus griseus - a dowitcher with a grey back;
is a kind of dowitcher
2. grayback(n = noun.animal) calidris canutus, greyback, knot - a sandpiper that breeds in the Arctic and winters in the southern hemisphere;
is a kind of sandpiper
is a member of calidris, genus calidris
The California gray whale. [1913 Webster]