potissime

From LSJ

Μὴ σπεῦδ', ἃ μὴ δεῖ, μηδ', ἃ δεῖ, σπεύδειν μένε → Ne agas celeria tarde, aut tarda celeriter → Unnötiges tu nicht, was nötig ist, tu gleich

Menander, Monostichoi, 344

Latin > English (Lewis & Short)

pŏtissĭmē: (pŏtissŭmē) and pŏtis-sĭmum (pŏtissŭmum),
I advv., v. potis fin. B.

Latin > French (Gaffiot 2016)

pŏtissĭmē, v. potissimum.