σιγᾶν ἄμεινον ἢ λαλεῖν ἃ μὴ πρέπει → it's better to keep silence than to say what's not appropriate (Menander)
P. and V. δύσκολος, δυσχερής, Ar. and P. κακοήθης, P. δύστροπος.
