effeci
From LSJ
Ἐς δὲ τὰ ἔσχατα νουσήματα αἱ ἔσχαται θεραπεῖαι ἐς ἀκριβείην, κράτισται → But for extreme illnesses, extreme remedies, applied with severe exactitude, are the best (Hippocrates, Aphorism 6)
Latin > French (Gaffiot 2016)
effēcī, parf. de efficio.