εἰν (ein)
εἰν is an Ancient Greek form of ἐν, meaning “in, among (+dat.)”. It is the preposition.
Found 126 times in the Ancient Greek texts on Socratos.
Where it is used
Apollonius Rhodius, Argonautica 1.460: ἔνθʼ αὖτʼ Αἰσονίδης μὲν ἀμήχανος εἰν ἑοῖ αὐτῷ
Sophocles, Ichneutae 382: [κ]ακῶς ἀκού[ειν οὐ πρέπει Διὸς γόνῳ.
Aristophanes, Clouds 1357: ὁ δʼ εὐθέως ἀρχαῖον εἶνʼ ἔφασκε τὸ κιθαρίζειν
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.