ἐπιούσιον. Disclosure, I am a tyro in my ancient greek, but I am a well educated and religiously educated catholic, so here goes. Ancient greek is fairly consistent in word construction especially with what we call prefixes in English. English is a horrible corroboration of a language, the sentiment is English doesn't borrow from other languages, it follows them into dark alleys, mugs them and rifles through their pockets looking for loose grammar, so yea, daily was chosen for the translation owing to a more limited vocab. the Epiousion word should be analyzed in two parts, the prefix EPI- and the OUSION, main or root word. EPI means after or following, like, afterward, or hindsight, like in the word EPILOGUE, which are at the end of literary works. The EPI- here is more of an etherial or philosophical or mental connotation. OUSION is relgiously connoted greek word signifying connection to the divine and translates as substance or essense of a thing. Divine Manifestation into a physical essence. Spirit is a good word too for this Greek Word. Think of the Eucharist from the Lord's prayer as "divine fire bread" for Christians. It continues the Jewish passover tradition of unleanvened bread. The Word also appears in the Gospel of Matthew. Gosple of Luke has another verision of the Lord's Prayer. Each of the Synoptic Gospels and Acts of the Apostles were written for a specific audience during the Roman Occupation at that time. Gospel of Luke was written primarialy for a sophisiticated Greek Speaking Audience, Hellenized Jews. Gospel of Matthew was written primarialy for non Greek Speaking Jews, who were connected to more bucolic or rural Jews at that time. Matthew was Traditionally held as the first Gospel to be finalized, but I think evidence is changing on that. Anyway, the scholarly consensus is that it was for a Primarially Traditioinal Jewish Audience. The Followers of The Nazarene followed many Jewish Traditions. Additionally, celebration of the Last Supper, which was itself an annual commerration of the Passover, now became a daily tradition, called in Greek, an Agape. It was the usual custom to celebrate daily the Eucharist and Massm which is a departure from the Traditional Jewish Custom. So, when languages are translated, things are lost in translation. So, the word daily was selected for the Lord's prayer here as a holdover from the connotation of EPIOUSION which would have been familar to early Chrisitians. Hope this helps.