What is the meaning of Addendum?

Something to be added; especially text added as an appendix or supplement to a document.

A postscript.

The height by which the tooth of a gear projects beyond (outside for external, or inside for internal) the standard pitch circle or pitch line.

inflection of addendus:

  1. nominative/accusative/vocative neuter singular
  2. accusative masculine singular

nominative/accusative/vocative neuter singular

accusative masculine singular

addendum (something to be added; especially text added as an appendix or supplement to a document)

Source: wiktionary.org