Source : Webster's Revised Unabridged Dictionary (1913)

Wherefore \Where"fore\, n.
   the reason why. [Colloq.]

Wherefore \Where"fore\, adv. & conj. [Where + for.]
   1. For which reason; so; -- used relatively.

            Wherefore by their fruits ye shall know them.
                                                  --Matt. vii.
                                                  20.

   2. For what reason; why; -- used interrogatively.

            But wherefore that I tell my tale.    --Chaucer.

            Wherefore didst thou doubt?           --Matt. xiv.
                                                  31.

Source : WordNet®

wherefore
     n : the cause or intention underlying an action or situation,
         especially in the phrase `the whys and wherefores' [syn:
         {why}]
     adv : for which reason; "wherefore do I receive this honor?" [syn:
            {wherefor}]