Definition of "postscriptum"

Meanwhile, I remain—Ever yours, / Jehu Face. / Postscriptums I hate; but I think you had better / Keep snug to yourself the contents of this letter.

1820, Humphry Martial [pseudonym], “Sir Jehu Face to Sir Cordovan Bristlemood”, in The Radical Letter-Bag, London: […] W. Wright, […], page 8

Postscriptum. — Scotland for ever! The Dane’s beneath the table, and Rab’s on the tap o’t, blawing like the deevil.

1827, M. Corbett, The odd volume, containing a letter purporting to be from King James VI of Scotland to Sandie Fotheringhame, Laird o'Powrie, signed: James, R.

This confidence so daintily tossed to the baron, in the fashion of a postscriptum, was evidently the compensation for five thousand francs.

1900, Honoré de Balzac, Anatole Cerfberr, La Comédie Humaine: Now for the First Time Completely Translated Into English

Sometimes she adds short postscriptums, but, though full of her doings and sayings, this correspondence contains but little that is really from Rosa Bonheur’s own pen.

1902, The Critic, volume 41, page 369

[…] read the mother’s report to the students and pointed out to them how she evidently could not yet believe in a definite change, this being clear from her postscriptums “I know of” and “though with all the Christmas excitement. .”

1956, The American Journal of Individual Psychology, volumes 12–13, page 169

Postscriptum for taxpayers: After having started with the high-temperature thriller we turned to applications of conventional superconductors.

2004, L. G. Aslamazov, A. A. Varlamov, The Wonders Of Physics