ETYMOLOGY
Latin, gerundive neuter pl. of tacere (to be silent)
EXAMPLE
“…With due rigour, Willelmus Sacrista, and his bibations and tacenda are, at the earliest opportunity, softly, yet irrevocably put an end to. The bibations, namely, had to end; even the building where they used to be carried on was razed from the soil of St. Edmundsbury, and ‘on its place grow rows of beans:’ Willelmus himself, deposed from the Sacristry and all offices, retires into obscurity, into absolute taciturnity unbroken thenceforth to this hour…”
From: Past and Present
By Thomas Carlyle, 1843
Lexicophilia 