Словарь синонимов английского языка - halfwitted

(adj) stupid, foolish, silly, simple, inane, asinine, moronic, imbecilic, doltish, rattle-brained, feeble-minded, attocerebral, cretinous, thick, non compos mentis, dim-witted, weak-minded, Colloq dumb, Brit dotty, barmy (in the crumpet): She had some halfwitted idea that she would win the lottery.