Tucked into the most familiar prayer in the world is a word that exists almost nowhere else. When the Lord’s Prayer asks for daily bread, the Greek behind daily is ἐπιούσιος (epiousios) — a word so rare that it appears essentially nowhere in surviving Greek literature outside the prayer itself. (A single supposed occurrence on an ancient papyrus shopping list, long cited as the lone exception, turned out on re-examination to be a misreading of another word.) Scholars call this a hapax legomenon — a word that appears only once. Epiousios is one of the most famous hapaxes in the Greek New Testament, and it has given translators trouble since the second century.

The trouble is that the word can be taken apart in more than one way, and the pieces mean different things depending on how you reassemble them. The prefix epi- means upon or for. The root could come from a verb meaning to be — which yields necessary for existence or supersubstantial — or from a word meaning to come — which yields for the coming day, that is, for tomorrow. The same handful of letters opens onto three quite different readings.

St. Jerome, translating the Bible into Latin around 400 AD, was so unsure that he rendered the word two different ways in the two places it appears. In Luke’s version he wrote quotidianum — daily. In Matthew’s he wrote supersubstantialem — supersubstantial, above-essence. The same word, in the same prayer, translated differently by the same translator. That is how slippery epiousios is.

Most modern English Bibles settle on daily, which has the advantage of being familiar and of fitting the prayer’s rhythm. But it’s worth knowing what may be hiding inside the line. If epiousios means for tomorrow, then give us today our bread for tomorrow echoes the wilderness manna, where God gave Israel exactly one day’s portion each morning — except before the Sabbath, when he gave tomorrow’s too. If it means necessary for existence, the line becomes give us today the bread we need just to be. And if it carries the supersubstantial sense the Catholic tradition has often heard, the line points past physical bread toward the bread of life — Christ himself, the sustenance the soul cannot live without.

There’s no need to choose between these for you. The honest answer is that epiousios may have meant several of these at once, and the Greek word is doing more work than any single English word can carry. What stays clear is the petition’s weight in its plainness: give us bread today. Whatever fullness lies inside the word, the prayer trusts the Father to provide what’s needed — and tomorrow it asks again.