From Longman Dictionary of Contemporary Englishdunderheaddun‧der‧head /ˈdʌndəhed $ -ər-/ noun [countable] old-fashioned STUPID/NOT INTELLIGENTsomeone who is stupid
Examples from the Corpus
dunderhead• It is obvious that the dunderheads in our federal government are incapable of achieving this compromise-without-disgrace.• The dunderheads etc wander in and out picking hungrily at the remains of a beetroot salad.Origin dunderhead (1600-1700) Perhaps from Dutch donder “thunder” + English head 