rascally adjective 1adverb 1forms 4 adjective1 •Like a rascal.He was speedily reassured, and with a large, white, rascally grin, and a glance at his charge, seemed to take me into partnership in his exalted trust. — 1899 adverb1 •In the manner of a rascal.“I hope,” said Jones, “you don’t intend to leave me in this condition.” “Indeed but I shall,” said the other. “Then,” said Jones, “you have used me rascally, and I will not pay you a farthing.” — 1749 formsmore rascally · rascallier · most rascally · rascalliest