Answer: addendum

AnswerCrossword Clue
ADDENDUM

Supplement

ADDENDUM

Supplement to a book

ADDENDUM

Postscript, e.g.

ADDENDUM
Book appendix
ADDENDUM
Postscript, say
ADDENDUMMemo p.s.
ADDENDUMCodicil
ADDENDUMSupplement to a book.
ADDENDUMSomething extra.
ADDENDUMSupplement.
ADDENDUMPostscript
ADDENDUMTack-on