名詞 lunkhead:

1. these words are used to express a low opinion of someone's intelligence
   同義詞：dunce, dunderhead, numskull, blockhead, bonehead, hammerhead, knucklehead, loggerhead, muttonhead, shithead, dumbass, fuckhead

lunk.head

n.Slang （名詞）【俚語】
A person regarded as stupid.
笨蛋：一個被認為愚蠢的人

來源：
Probably alteration of lump
可能為 lump的變化
head
head

【引伸】
lunk.head.ed
adj.（形容詞）