Addendum

n. addition; attachment

In the plural, both the Latin addenda and the English adaptation addendums are acceptable.
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Noun
1. textual matter that is added onto a publication; usually at the end
(synonym) supplement, postscript
(hypernym) matter
(hyponym) appendix
(part-holonym) back matter, end matter

n. addend, number which has been added to another (Mathematics)

n. addendum, addition; attachment