What is the meaning of Postscriptum?

A thing that has been written afterwards; something appended in writing.

post scriptum

alternative form of post-scriptum

postscript, post scriptum

accusative supine of postscrībō

postscriptum (annotation at the end of a letter or article used to inform the reader of something loosely related or unrelated to the subject of the letter or article)

postscriptum (series of additional pieces of information given at the end of a programme, speech, or book, or in the form of a separate text, to clarify, supplement, or summarize an earlier message)

Source: wiktionary.org