fatuous UK /ˈfæt.ju.əs/US /ˈfæ.tʃu.əs/ adjective1 •Obnoxiously stupid; vacantly silly; content in one's foolishness.Maude Lebowski: Lord. You can imagine where it goes from here. The Dude: He fixes the cable? Maude: Don't be fatuous, Jeffrey. — 1998 formsmore fatuous · most fatuous