Emily Dickinson Lexicon

ROOK, n.¹ [Sax. hroc; G. roche; Dan. roge, raage, a rook and krage, a crow. This word belongs to the root of crow or is rather the same word dialectically varied; Dan. krage; Sw. kraka; G. krähe; D. kraai; L. graculus; probably from its voice; Ir. grag, gragam. See Crow and Croak.]

1. A fowl of the genus Corvus, the fowl mentioned by Virgil under this name. This fowl resembles the crow, but differs from it in not feeding on carrion, but on insects and grain. In crows also the nostrils and root of the bill are clothed with feathers, but in rooks the same parts are naked, or have only a few bristly hairs. The rook is gregarious. – Encyc.
2. A cheat; a trickish, rapacious fellow. – Wycherley.