Webster's Revised Unabridged Dictionary · 1913

Thereby

Thereby , adverb

1.
By that; by that means; in consequence of that.
Acquaint now thyself with him, and be at peace; thereby good shall come unto thee. — Job xxii. 21
2.
Annexed to that.
Thereby hangs a tale. — Shakespeare
3.
Thereabout; -- said of place, number, etc. — Chaucer