The story
- Proto-Indo-European*h₂eǵ-
- Proto-Indo-European*h₂éǵeti
- Proto-Italic*agō
- Latinagō
- Latinagenda
- English todayagenda
From Latin agenda (“things that ought to be done”), future passive participle (gerundive) of agō (“to do, act, make”).
Etymology from Wiktionary, CC BY-SA 4.0.