adj. 25B6; adjective SILLY, inane, unintelligent, foolish, stupid, fatuous, idiotic, brainless, witless, vapid, vacant, empty-headed; informal dumb, gormless, moronic, brain-dead.
intelligent.
VACUOUS
Meaning of VACUOUS in English
Concise Oxford thesaurus English vocabulary. Краткий оксфордский словарь английского языка тезаурус. 2012