addendum

Definitions:

An appendix; something added.
- Etymological and pronouncing dictionary of the English language. By Stormonth, James, Phelp, P. H. Published 1874. (noun) (n.) (noun)
Something to be added.
- The Clarendon dictionary. By William Hand Browne, Samuel Stehman Haldeman. Published 1894. (noun) (n.) (noun)
A thing or things to be added; an appendix.
- Nuttall's Standard dictionary of the English language. By Nuttall, P.Austin. Published 1914. (noun) (n.) (noun)
A thing to be added: an appendix.
- The american dictionary of the english language. By Daniel Lyons. Published 1899. (noun) (n.) (noun)

Usage examples:

Maspero, but is rather intended as an appendix or addendum to his work, briefly recapitulating and describing the discoveries made since its appearance.
- History Of Egypt, Chaldæa, Syria, Babylonia, And Assyria In The Light Of Recent Discovery by L.W. King and H.R. Hall
On the hither side of one of the two streets close under him, his office- the old, first one, reopened on his return- stood closed, the sign renovated and tacked up once more, and the early addendum Gentleman, still asserting itself, firmly though modestly, beneath the new surface of repair.
- John March, Southerner by George W. Cable
The instructions were prepared very carefully, and after Governor Fish and I had gone over them for the last time I wrote an addendum charging him that above all things he should handle the subject of the Alabama claims with the greatest delicacy.
- Memoir of John Lothrop Motley, Complete by Oliver Wendell Holmes, Sr. Last Updated: February 6, 2009