Definition of "addendum" in English

noun

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

   • An addendum was added to the contract to clarify payment terms.
   • The author included an addendum at the end of the book.

2. A postscript.

3. (engineering) 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.