ras·cal·ly I. \ˈrask(ə)lē, ˈraas-, -li, chiefly Brit ˈrȧs-\adjective Etymology:rascal (I) + -ly 1.obsolete: of or relating to the rabble 2.: of or characteristic of a rascal : meanly tricky or dishonest : mean, base, worthless < notorious for their quarrelsome and rascally proclivities — Jack London > < our rascally porter is fallen fast asleep — Jonathan Swift > II. adverb : in a rascally fashion