What does the 인 in 인이 박이다 mean?

ANSWER: Well, it is the first definition under 인 in my Korean dictionary and is defined as 늘 되풀이하여 배다시피 한 버릇, which can be translated as "a habit formed by almost constant repetition."

And listed with that definition is the idiom 인이 박이다, which is defined as 버릇이 되다시피 깊이 배거나 빠지거나 굳어지다. So, 인이 박이다 can be translated as "To become deeply ingrained or hardened to the point of becoming a habit."

Interestingly, the above 인 is the only pure-Korean 인 listed under "인" in my Korean dictionary, if you do not count the particle 인 or the 인 that refers to the English preposition "in." And the fact that it is the only pure-Korean 인 is probably why it was listed before all the Sino-Korean 인s.

So, basically 인 means "a habit formed by almost constant repetition," but, for some reason, that definition is not listed among the 인s in my Korean-English dictionary. Why?

ANSWER: Maybe because it is not used by itself and is only used in the idiom 인이 박이다, and if that is true, maybe it is not really a pure-Korean word. Maybe, it was originally the Sino-Korean 인 (印), which means "a seal" or "a stamp"?

Now, let's look at the 박이다 part of the idiom. My Korean-English dictionary lists the idiom 인이 박이다 under the second definition of the verb 박이다, which is defined as "to become a habit." But that seems a little odd since 인이 박이다 would then literally translate as "a habit becomes a habit." It makes me think that the only reason 박이다 is defined as "to become a habit" is because of the idiom 인이 박이다. Why not just use the third definition: "to be put into print"? Then, 인이 박이다 could be translated as "a habit becomes imprinted."

Finally, there is also the Korean verb 박히다, which can be defined as "be nailed," "be driven into," "be stuck in," and also "be printed." So, besides having similar pronunciations, 박이다 /바기다/ and 박히다 /바키다/ seem to have similar meanings, but 박히다 is a verb that is more commonly used in Korea than 박이다, which makes me wonder if 박이다 is just a misspelling of 박히다.

And, to add to the confusion, my "Korean Language Example Dictionary" (국어용례사전) shows that the idiom is NOT 인이 박이다 but 인이 박히다.

So, which spelling and pronunciation do Koreans use: 인이 박이다 or 인이 박히다? Well, it seems to depend on the Korean: