- The definition of an ignoramus is someone who lacks knowledge or is dumb.
An example of an ignoramus is someone who doesn't know their left from their right.
A man acting like an ignoramus.
ignoramus definition by Webster's New World
Origin: ; from the name of a lawyer in Geo. Ruggle's play Ignoramus (1615); Classical Latin literally , we take no notice (a legal term formerly written on a bill of indictment by a grand jury that finds it to be not a true bill)
ignoramus definition by American Heritage Dictionary
noun pl. ig·no·ra·mus·es
Origin: From New Latin ignōrāmus, a grand jury's endorsement upon a bill of indictment when evidence is deemed insufficient to send the case to a trial jury, from Latin, we do not know, first person pl. present tense of ignōrāre, to be ignorant; see ignore.