WordNet (r) 3.0 (2006):

greyback
    n 1: `Johnny' was applied as a nickname for Confederate soldiers
         by the Federal soldiers in the American Civil War;
         `greyback' derived from their grey Confederate uniforms
         [syn: Rebel, Reb, Johnny Reb, Johnny, greyback]
    2: a dowitcher with a grey back [syn: greyback, grayback,
       Limnodromus griseus]
    3: a sandpiper that breeds in the Arctic and winters in the
       southern hemisphere [syn: knot, greyback, grayback,
       Calidris canutus]