From Longman Dictionary of Contemporary Englishignoramusig‧no‧ra‧mus /ˌɪɡnəˈreɪməs/ noun (plural ignoramuses) [countable] old-fashioned NOT KNOWsomeone who does not know about things that most people know about
Examples from the Corpus
ignoramus• To think otherwise, it seems, is to reveal oneself as an ignoramus who does not know enough characters.• You are not an ignoramus if you have never heard of marsanne, roussanne and viognier.• She also tried hard to revive interest in Idomeneo, thus proving that she was no musical ignoramus.• Andrew Jackson, the first president from the western frontier, was unjustly accused of bigamy and derided as an unschooled ignoramus.• Edward the Eighth, you ignoramus.Origin ignoramus (1500-1600) Latin “we do not know”, from ignorare; → IGNORE 