a single item of business to be considered or acted upon; one thing on an agenda (the technically correct singular of 'agenda').
Latin neuter singular gerundive of 'agere' (to do/act). In formal Latin grammar, 'agenda' is already a plural, making 'agendum' the proper singular form, though modern English rarely uses it.
Most English speakers have no idea that 'agenda' is technically plural—we've reinterpreted it as singular, so saying 'agendum' sounds hilariously formal, yet it's technically the grammatically correct Latin singular form.
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