ὑπανοίγειν

From LSJ

νέῳ δὲ σιγᾶν μᾶλλον ἢ λαλεῖν πρέπει → it's fitting for a young man to keep silence rather than to speak (Menander)

Source

Greek > English (Woodhouse Verbs Reversed)

(see also ὑπανοίγω): tamper with, open secretly