Etymology From New Latin postscriptum, from Latin, neuter of postscriptus, past participle of postscrībō (“write after”), from post (“after”) + scrībō (“write”). By surface analysis, post- + script.
1
An addendum to a letter, added after the author's signature.
As a rule Julian dictated to secretaries, and so fast that Libanius says the "tachygraphers" were unable to keep pace with him, but certain postscripts are marked "with his own hand."1913, Flavius Claudius Iulianus, “Letters of Julian”, in Emily Wilmer Cave Wright, transl., The Works of the Emperor Julian, volume III, Introduction to the letters:
2
An addition to a story, play, etc. after its completion.
In a moving post-script to the novel, Forster tells the reader that the book was inspired by a visit to the home of Edward Carpenter.1974 February 2, Allen Young, “Reviews”, in Gay Community News, volume 1, number 32, page 7:
And then a curious postscript: I share your dislike of the shortening of names but I must say that I'm not sure 'Alexandra' is entirely suitable for you. It seems to me that you require a name with rather more brio. I see you as a 'Lexie'. What do you think?2010, Maggie O'Farrell, The Hand That First Held Mine, Headline, →ISBN, page 34:
Etymology From New Latin postscriptum, from Latin, neuter of postscriptus, past participle of postscrībō (“write after”), from post (“after”) + scrībō (“write”). By surface analysis, post- + script.
1
To extend (a letter or another document) with additional remarks.