An idiom of a year

Since a year 2001 Korean scholars (교수신문) choose an idiom of a current year. This is 4-characters expression (사자성어) that reflects an image of the year in the most suitable way and perfectly characterize it.

사자성어 are supposed to be learnt by pupils at school but it's extremelly hard to keep in mind it!! It seems to me that idioms chosen are the most diffucult ((

Well, there is a list of idioms:

Let's sort out this idiom one by one starting with the year 2001:

2001 - 오리무중

 五- five
 里- a village, ri
 霧- a mist, a fog
 中- the middle

The meaning of this idiom is"to be befogged", "to be puzzled"