Fat'u·ous adjective [ Latin fatuus .] 1. Feeble in mind; weak; silly; stupid; foolish; fatuitous. Glanvill. 2. Without reality; illusory, like the ignis fatuus . « Thence fatuous fires and meteors take their birth.» Danham. Found on http://www.encyclo.co.uk/webster/F/12