Emily Dickinson Lexicon

ARCH, a. [It. arcare, to bend, to arch, to cheat or deceive, from arco, L. arcus, a bow; G. arg, cunning, arch, bad; It. arg, crafty, roguish; Sw. and Dan. arg, id. The Teutonic arg, appears to be allied to arch, and to be the Eng. rogue. This circumstance, and the Arm. goarec, (see Arc,) indicate that the radical letters in arc, arch, αρχη, are Rg. The radical sense of bend is to strain.]

Cunning; sly; shrewd; waggish; mischievous for sport; mirthful; as we say in popular language, roguish; as, an arch lad.