silentium

Silentium, silentii, n., second declension, formed from the present participle of sileo, silere, silui, "be silent". The ablative silentio does most of the work in the corpus as an ablative of manner: "silentio" on its own means quietly, without fuss, and "cum silentio" the same with the preposition supplied.

Note that Latin makes silence something you do rather than something that happens: "silentium facere" is to make silence, either by shutting up yourself or by getting a crowd to. Monastic Latin turns it into an institution, the magnum silentium that covers the hours between Compline and Prime, and that is the sense the ecclesiastical corpus mostly wants. The neuter plural silentia is poetic rather than odd.