Get the FREE one-click dictionary software for Windows
or the iPhone/iPad and Android apps
Adjective: nitwitted  'nit,wi-tid
Usage: informal
  1. (of especially persons) lacking sense, understanding or judgment
    "His nitwitted remarks made everyone in the room cringe";
    - senseless, soft-witted, witless

See also: daft [Brit, informal], dumb, foolish, imbecile, imbecilic, stupid