postscript Meaning, Definition & Usage

  1. noun a note appended to a letter after the signature
    PS.
  2. noun textual matter that is added onto a publication; usually at the end
    addendum; supplement.

WordNet

Post"script noun
Etymology
L. postscriptus, (assumed) p. p. of postscribere to write after; post after + scribere to write: cf. F. postscriptum. See Post-, and Scribe.
Definitions
  1. A paragraph added to a letter after it is concluded and signed by the writer; an addition made to a book or composition after the main body of the work has been finished, containing something omitted, or something new occurring to the writer. Abbrev. P. S.

Webster 1913