Ask at the forum if you have an Ancient or Modern Greek query!

ἐπειδὴ

Ὦ ξεῖν’, ἀγγέλλειν Λακεδαιμονίοις ὅτι τῇδε κείμεθα τοῖς κείνων ῥήμασι πειθόμενοι. → Go tell the Spartans, stranger passing by, that here, obedient to their laws, we lie.
Simonides of Kea

Greek (Liddell-Scott)

ἐπειδὴ: ἢ ἐπεὶ δὴ (ὡς γράφεται νῦν παρ’ Ὁμ.) ἐντονώτερος τύπος τοῦ ἐπεὶ, ἴδε ἐν λ. ἐπεί.