Webster's Revised Unabridged Dictionary · 1913

Wherefore

Wherefore , adverb and conjunction

[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

Wherefore , noun

the reason why. [Colloquial]