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
Latin > English (Lewis & Short)
pŏtissĭmē: (pŏtissŭmē) and pŏtis-sĭmum (pŏtissŭmum),
I advv., v. potis fin. B.
Latin > French (Gaffiot 2016)
pŏtissĭmē, v. potissimum.