You searched for: “agenda
addenda, addendum, agenda
addenda (uh DEN duh) (noun, plural)
Things to be added, as in a supplement or an appendix: The author included three addenda of new materials in his book.
addendum (uh DEN dum) (noun), singular
Something that has been added in a written document: The report has an addendum clarifying certain procedural actions.
agenda (uh JEN duh) (noun)
A list of things to be done at a meeting; schedule, program: What is on your agenda today?

Agenda was originally the plural of Latin "agendum" (thing to be done) and is still considered by some to be a plural form.

In modern English; however, agenda is usually considered as the singular form with agendas the plural: What is on the agenda for the meeting?

The secretary kept track of the two executives’ agendas.

After his secretary printed the new agenda, Gordan realized he also needed the revised addenda which should be printed in an addendum.

agendum (s) (noun), agenda (pl)
Things to be done, memoranda of items to be considered at a meeting. Agenda was plural in form in the original Latin, but now is often used as a singular in English, in the sense of "list"; and followed by a singular verb.

So well established is agenda as a singular that agendas is now commonly heard and seen as the plural form; however, the correct Latin singular is agendum; as, "The agendum is whether we want an extended school year or not."

"The agenda have been established for the meeting."

You have the choice to follow hoi polloi or to write it "correctly".