dimwit
From Longman Dictionary of Contemporary Englishdimwitdim‧wit /ˈdɪmwɪt/ noun [countable] spoken STUPID/NOT INTELLIGENTa stupid person —dim-witted adjectiveExamples from the Corpusdimwit• Everyone knows that ducks are dimwits.• Jones and Cook were simply likeable dimwits.• Don't let that dimwit Larry near my computer.• Shore actually plays the smarter of two dimwits who mistakenly lock themselves in a Biosphere-type isolation experiment.