Latin, a gerundive form the verb agere 'to do,' with the added sense of necessity, meaning 'what ought to be done'
agendum (classical plural: agenda; Anglophone plural: agendums (rare))
- (usually plural) A task which ought to be done.
Agendum is a word now so common in the plural that its plural form agenda is now generally taken to be a collective singular form, with the special meaning of a list of tasks which are to be done. A similar case is datum and its plural data which is now commonly taken to be a collective singular and synonymous with 'information'.
The American Heritage Dictionary's entry and usage note for 'agenda'
'agendum' in the AHD
Category:English nouns with irregular plurals
neuter singular gerundive of agere (which see)