Thereby is defined as because of something.
An example of thereby is when someone signed a confession and were then put in jail; they confessed thereby they are in jail.
- by or through that; by that means
- connected with that: thereby hangs a tale
- Archaic thereabouts
- By that means; because of that.
- In connection with that: “And thereby hangs a tale” (Shakespeare).
- (formal) By it, by that.