Noun
a stupid person; these words are used to express a low opinion of someone's intelligence
Source: WordNetI've pretty much behaved like a knucklehead my entire life. Cameron Diaz
A roast is like a get-together where people come down and talk about you and dog you out, the way you came up, the knucklehead things that you did, stuff like that. Bootsy Collins
In the eighties, a self-assured knucklehead whose unsurpassable hollowness and hackneyed sentiments and absolute blindness to every historical complexity became the object of national worship and, esteemed as a "great communicator” no less, won each of his two terms in a landslide. Philip Roth
Admittedly, there are those knucklehead bottleneck drivers that are going well below the speed limit and think they own the road. Source: Internet
Mitchel, p. 92 In 1936, the 61E and 61EL models with the " Knucklehead " OHV engines was introduced. Source: Internet
You can feel Bethan’s pain and embarrassment while reveling in her successes and in her everyday teen angst, which include her brushes with knucklehead class bully Stan Priest (Aled ap Steffan) and her tenuous relationships with the school faculty. Source: Internet