wherein

• POS: Pronoun, Adverb
• HYPHEN: where=in

CIDE DICTIONARY

wherein, adv. 

•  In which; in which place, thing, time, respect, or the like; -- used relatively.  [1913 Webster]

  "Her clothes wherein she was clad."  [1913 Webster]

  "There are times wherein a man ought to be cautious as well as innocent."  [1913 Webster]
•  In what; -- used interrogatively.  [1913 Webster]

  "Yet ye say, Wherein have we wearied him!"  [1913 Webster]

OXFORD DICTIONARY

wherein, conj. & adv. formal
--conj. in what or which place or respect.
--adv. in what place or respect?