where·in /hwɛrˈɪn, hwær, wɛr, wær, (ˌ)(h)wɚ/
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.
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
3: in which; where; "the particular state wherein you reside"
4: in what; "wherein consists this matter?"