κατασιωπητέον
From LSJ
Χρὴ τῶν ἀγαθῶν διακναιομένων πενθεῖν ὅστις χρηστὸς ἀπ' ἀρχῆς νενόμισται → When a good man is hurt, all who would be called good must suffer with him
English (LSJ)
one must keep silence, Isoc.12.96.
Greek (Liddell-Scott)
κατασιωπητέον: ῥημ. ἐπίθ., πρέπει νὰ κατασιωπᾷ τις περί τινος, περί τινος κατασιωπητέον Ἰσοκρ. 252D.
French (Bailly abrégé)
adj. verb. de κατασιωπάω.