HEREWITH

hereby, herewith

(adverb) (formal) by means of this; “I hereby declare you man and wife”

Source: WordNet® 3.1

Etymology

Adverb

herewith (not comparable)

with this; especially, with this letter or communication

by this means

in this way, hereby

Source: Wiktionary

Here*with", adv.

Definition: With this.

Source: Webster’s Unabridged Dictionary 1913 Edition