συμβλήσεαι

From LSJ

πολλὰ μεταξὺ πέλει κύλικος καὶ χείλεος ἄκρου → there is many a slip twixt cup and lip, there's many a slip twixt cup and lip, there's many a slip 'twixt cup and lip, there's many a slip twixt the cup and the lip, there's many a slip 'twixt the cup and the lip

Source

French (Bailly abrégé)

f. épq. 2ᵉ sg. de συμβάλλω.

Russian (Dvoretsky)

συμβλήσεαι: эп. 2 л. sing. fut. med. к συμβάλλω.