Appendix, addendum, annexure and attachment

Reader’s question: What’s the difference between an appendix and an addendum?

Can they be used interchangeably or should we be using one over the other in specific circumstances?

Answer: My first reaction was that these terms are not interchangeable, but when I looked in a dictionary, I was surprised to find that one definition of an addendum was ‘an appendix’. Another definition was ‘an addition’, and that’s how I regard an addendum.

Being truly pedantic, I would distinguish between these words as follows:

An appendix supplements the body of a document, providing detailed information that not everyone will want to read. Appendices are often statistical, historical or technical.

An addendum is extra information that the writer discovered after writing the report, such as a new study on the topic. It’s a bit like a PS.

These words both have two possible plurals:

appendices or appendixes

addenda or addendums

Annexure and attachment

I am writing an addendum to this original post.

Since responding to the original question, I have seen the words annexure and attachment used in board papers to describe appendices.

However, I haven’t seen addendum in the board paper world. (The Macquarie Dictionary recognises annex, but not annexure.)

Learn more about words

Register for my online Business Writing course to learn more about words. You’ll also brush up on your general writing skills.

Sign up for my monthly e-newsletter to receive writing and grammar tips.