Source : Webster's Revised Unabridged Dictionary (1913)

Wherein \Where*in"\, adv.
   1. In which; in which place, thing, time, respect, or the
      like; -- used relatively.

            Her clothes wherein she was clad.     --Chaucer.

            There are times wherein a man ought to be cautious
            as well as innocent.                  --Swift.

   2. In what; -- used interrogatively.

            Yet ye say, Wherein have we wearied him! --Mal. ii.
                                                  17.

Source : WordNet®

wherein
     adv 1: in regard to which; "a case wherein he took an active part"
     2: in the course or during which; "a period wherein he did not
        work"
     3: in which; where; "the particular state wherein you reside"
     4: in what; "wherein consists this matter?"