noun.
A message appended at the end of a letter after the writer's signature.
noun.
Additional information appended to the manuscript, as of a book or article.
The Century Dictionary and Cyclopedia
noun.
An addition made to a written or printed composition as an afterthought, or to state something that has been omitted.
noun.
More commonly, a paragraph added to a letter which has already been concluded and signed by the writer.
noun.
Abbreviated P. S.
the GNU version of the Collaborative International Dictionary of English
noun.
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.