Plural of addendum; sections added to the end of a document or book containing additional information or corrections.
From Latin addendum (a thing to be added), with English plural '-s' added. While 'addenda' is the traditional Latin plural, 'addendums' emerged as English speakers anglicized the word.
English speakers debated for centuries whether to use 'addenda' or 'addendums'—we actually use both, showing how English happily steals Latin words but refuses to always follow Latin grammar rules!
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