addendum

 
Pronunciation: /əˈdɛndəm/

noun (plural addenda /-də/)

  • 1an item of additional material added at the end of a book or other publication.
  • 2 Engineering the radial distance from the pitch circle of a cogwheel or wormwheel to the crests of the teeth or ridges. Compare with dedendum.

Origin:

late 17th century: Latin, 'that which is to be added', gerundive of addere (see add)