Agenda is a word that English stole from Latin grammar and then broke the rules of. In Latin, agenda is the neuter plural gerundive of agere ('to do, drive'), meaning 'things that must be done'. The singular form is agendum — a single item requiring action. Medieval church Latin used agenda for lists of liturgical business, and English adopted it in the early seventeenth century for meeting items. By the nineteenth century, English speakers treated 'agenda' as a singular collective noun (one agenda, many agendas), a shift that would have puzzled a Roman grammarian. The figurative sense — someone's 'agenda' as their hidden aims — is surprisingly recent, dating only to the 1970s. The root agere is among the most prolific in the English lexicon: act, agent, agile, navigate, essay, examine, and ambiguous all trace back to this single Latin verb meaning 'to set things in motion'.