numbskull
noun
numb·skull ˈnəm-ˌskəl 
variants or less commonly numskull
1
: a dull or stupid person : dunce
2
: a thick or muddled head
Example Sentences
Recent Examples on the Web Four women enjoying a retreat at a secluded lakeside cabin are attacked by three numbskulls and turn the tables on them, becoming the torturers. 
Chris Ball, cleveland.com, 1 Apr. 2018 Thank you to US press and other numbskulls who put him there. Colin Stutz, Billboard, 1 June 2017
Chris Ball, cleveland.com, 1 Apr. 2018 Thank you to US press and other numbskulls who put him there. Colin Stutz, Billboard, 1 June 2017 Word History
Etymology
numb entry 1 + skull entry 1
First Known Use
1697, in the meaning defined at sense 1