gorm ‧ less /ˈɡɔːmləs $ ˈɡɔːrm-/ BrE AmE adjective British English informal
[ Date: 1800-1900 ; Origin: gaumless 'lacking understanding' (18-20 centuries) , from gaum 'understanding' (18-19 centuries) , from Old Norse gaumr 'heed, attention' ]
very stupid:
a gormless grin
—gormlessly adverb