define ignoramus
Webster Dictionary(5.00 / 1 vote)Rate this definition: 1  Ignoramus(noun) we are ignorant; we ignore; -- being the word formerly written on a bill of indictment by a grand jury when there was not sufficient evidence to warrant them in finding it a true bill. 2  Ignoramus(noun) a stupid, ignorant person; a vain pretender to knowledge; a dunce.