Learn how to say Addendum correctly in English with this tutorial pronunciation video.
Oxford dictionary definition of the word addendum:
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.
late 17th century: Latin, ‘that which is to be added’, gerundive of addere (see add)