Do Not Know - Ways to Approach this Problem
The problem: In the Lord's Prayer, Matthew and Luke use the word epiousios to describe the bread. Unfortunately we are not certain exactly what epiousios means.
There are a number of ways in which we can approach the problem of the unknown word in the Lord's Prayer. Whilst they may not give a definitive answer, they may provide a way in which possible meaning can emerge.
One of the first skills we gain when learning to read is to skip unknown words. This does not mean that we ignore them, but that we can gain an impression of their meaning from their context. This is an intratextual approach. We are looking for clues within (intra) the text itself.
Just imagine you are reading a novel and you come across a word ('maridly') you do not know.
Although we cannot tell from this section quite what game John is playing, the context is enough to give us a clue about the meaning of the word 'maridly'. The context suggests an action which is half-hearted and imprecise. In fact, the context tells us enough about the impact of John's attitude upon his action that we do not really need 'maridly' at all. Here textual context provides enough information to suggest a fairly secure definition.
Another strategy for decoding an unknown word is by looking at its form. Does it look or sound like a more familiar word. It may simply be an incorrect spelling (quite a common occurrence in hand-copied documents). It might however be related to a similar word (eg. familial from family).
It might strike some readers that maridly sounds a bit like 'mardy' (grumpy, moody, surly). Well, that appears to fit the context quite well. Maridly also sounds a bit like 'married'. However, there is little in the context to suggest this type of meaning.
One further way of understanding the meaning of a word is to find out how it is used in a different book or text. In other words we look for it occurring outside (extra) the text. For us today, the definitive answer should be found in the dictionary. Failing that, we might have another book where the writer uses maridly.
Although this excerpt still does not give us an exact definition, it certainly throws more light on its use in the first passage and goes some way to giving us a greater degree of precision. Our first conjecture about half-hearted appears to have been correct.
The problem with extratextual comparison is that words can change their meanings in different contexts.
The word 'bad' can denote something totally different when it is used (or has been used) within some parts of youth culture (to mean the opposite - 'good') from that used in everyday language. Within the context of the early Church we must also be careful about changes in meaning. When the New Testament literature was being written, common words were beginning to take on a new meaning (or new significance) within the Christian community. For example, 'gospel' and 'justification' begin to take on a more technical meaning. This means that words found outside Christian literature do not always reflect their significance within the church.
It should be noted here, that it there have been suggestions of an independent occurrence of this word. In 1925, Albert Debrunner discovered a Greek papyrus which contained household accounts and listed various purchases of commodities. However, this papyrus can no longer be found so that the reading remains unverified (see Bruce Metzger's article 'How many times does epiousios occur outside the Lord's Prayer'. Expository Times. 69. 1957/8. 52-4.).