From the 1930's (circa). Refers to a person of questionable intelligence. The size of the brain being given relative size of a human knuckle. Similar to pinhead.
Engine produced by the Harley Davidson Motorcycle Company from(1936 to 1947). The engine consists of an overhead-valve v-twin design with covers on the valves that resembled knuckles, hence the name of "knucklehead".
An honors physics student of ability but who lacks the conventional expression of said ability (i.e. homework completion, class appropriateness). May or may not get high grades.
A dickies wearing, cheap flannel shirt wearing, gangbangin Mexican with a shaved head. Almost always act like dicks.
Ah fuck dood... I was cruisin outta school and this big fuckin knucklehead came up to me and was like 'Eh Vato, Gimme your pinche money esse!' So I yelled for la migra, and wouldn'tcha know, the mafacker ran away! Fuckin hate knuckleheads.
