An addendum is something that is added to a document. Your rental lease might have an addendum attached to it. If a firm’s Bid Documents had a change after the fact, it was an addendum that added additional information to the documents.

Addendum is the singular form. Addenda is the plural form.

With reference to our industry, Bid Documents contain the plans, specifications, and estimates that are sent out to Bidders. If, for example, the Bidders then have questions or bring up a situation that might prompt a change to the Bid Documents, an addendum would be issued. After the bidding process, if there were any changes, the Owner might issue a set of Conformed Documents that would include that one addendum, or if Bidders prompted a number of different changes, then all of the addenda would be incorporated into the Conformed Documents.

It's easy to confuse the singular and plural forms; just remember that if there’s more than one addendum to the document, it’s considered plural, so addenda is the correct word to use.

Special thanks to our authors - Judy Beebe, FSDA and Carol Wanda Spradlin, CDFA - both with the SDA Pacific Northwest (formerly Seattle) chapter.