ἐπειδήπερ (epeideper)
ἐπειδήπερ is an Ancient Greek form of ἐπεί, meaning “after, when, since, because”. It is the conjunction.
Found 206 times in the Ancient Greek texts on Socratos.
Where it is used
Thucydides, History of the Peloponnesian War 6.18.3: καὶ οὐκ ἔστιν ἡμῖν ταμιεύεσθαι ἐς ὅσον βουλόμεθα ἄρχειν, ἀλλ’ ἀνάγκη, ἐπειδήπερ ἐν τῷδε καθέσταμεν, τοῖς μὲν ἐπιβουλεύειν, τοὺς δὲ μὴ ἀνιέναι, διὰ τὸ ἀρχθῆναι ἂν ὑφ᾽ ἑτέρων αὐτοῖς κίνδυνον …
New Testament, Luke 1.1: ΕΠΕΙΔΗΠΕΡ ΠΟΛΛΟΙ ἐπεχείρησαν ἀνατάξασθαι διήγησιν περὶ τῶν πεπληροφορημένων ἐν ἡμῖν πραγμάτων,
Source: Socratos (socratos.org), a free reader for Ancient Greek and Latin. Grammar from the Perseus Treebank and Morpheus; dictionary entries from Liddell-Scott-Jones, A Greek-English Lexicon (Perseus Digital Library, CC BY-SA). Counts are from the texts on Socratos.