What does the 대 in 대머리 mean?

 ANSWER: Big?

The Korean word for "head" is 머리, and the Korean word for "bald head" is 대머리, so does the 대 is 대머리 mean "bald"?

I have read HERE that 대 might be a dialectical word for 민둥, which means "bare" or "bald," but I wonder if it might instead have come from the Chinese character for "big," which is 大 (대).

As men get older, many gradually go bald to some extent. That might have looked to some Koreans as if the men's heads (머리) were growing bigger (대 大) while their hair stayed the same size. And that might have led some Koreans to jokingly refer to such men as "big heads" (대머리).

So could it be that the word 대머리 started out as a joke?

From Dong-A's Prime Korean-English Dictionary