plural addenda /-ˈdɛndə/ /əˈdɛndə/ or addendums plural addenda /-ˈdɛndə/ /əˈdɛndə/ or addendums Learner's definition of ADDENDUM
[count]
: something that is added
especially : a section of a book that is added to the main or original text增加的部分;(尤指书籍的)补遗,补篇