Webster's Revised Unabridged Dictionary · 1913

Wherein

Wherein , adverb

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