pith
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
English > Greek (Woodhouse)
substantive
P. ἐγκέφαλος, ὁ (Xen.), μυελός, ὁ (Aristotle).
Met., chief point: P. τὸ κεφάλαιον.