Definition of "thenceforth"

...to the end, that all such foes to the rights of British-America may be publicly known, and universally contemned as the enemies of American liberty; and thenceforth we respectively will break off all dealings with him or her.

1774, First Continental Congress, The Articles of Association

Furthermore: you must know that when the second iron is thrown overboard, it thenceforth becomes a dangling, sharp-edged terror, skittishly curvetting about both boat and whale, entangling the lines, or cutting them, and making a prodigious sensation in all directions.

1851, Herman Melville, chapter 63, in Moby Dick

The fear of losing Joe’s confidence, and of thenceforth sitting in the chimney corner at night staring drearily at my forever lost companion and friend, tied up my tongue.

1861, Charles Dickens, chapter VI, in Great Expectations

I decided to act thenceforth with great caution; not to leave the house, but somehow leave Portsmouth.

1927-1929 — Mahatma Gandhi, An Autobiography or The Story of my Experiments with Truth, "Nirbal Ke Bala Rama", translated 1940 by Mahadev Desai

Here his hand trembled as he set his pen to the proclamation that declared slaves thenceforth and forever free.

1994 February 12, Bill Clinton, Presidential Radio Address