opos
From LSJ
Ἀναξαγόρας δύο ἔλεγε διδασκαλίας εἶναι θανάτου, τόν τε πρὸ τοῦ γενέσθαι χρόνον καὶ τὸν ὕπνον → Anaxagoras used to say that we have two teachers for death: the time before we were born and sleep | Anaxagoras said that there are two rehearsals for death: the time before being born and sleep
ŏpos: i, m., = ὀπός>,
I juice, sap, Cael. Aur. Acut. 3, 8, 96.