ARCH

adj. 1 chief, principal, prime, primary, pre-eminent, foremost, first, greatest, consummate, major Moriarty was Holmes's arch-enemy 2 clever, cunning, crafty, roguish, tricky, shrewd, artful, sly, designing Brendan loves to play his arch pranks on unsuspecting friends 3 waggish, saucy, mischievous, prankish I could tell from the lad's arch expression that he had thrown the snowball