What does “breaking bread” mean in ancient texts (Mark 14:22, Acts 2:42, 2:46, etc.)?
Look at one of the contemporary types of bread, the panis quadratus. The top is scored into equal sections. Usually there are eight sections, but an image from Pompeii shows a candidate for office distributing larger breads with 12 sections.
The panis quadratus simplified the task of distribution of bread within a group. Every person received the same quantity of bread. I suggest that at meetings of every sort of fellowship group, the breaking of the panis quadratus and its distribution symbolized and reified the equality of the members. Perhaps the form of the panis quadratus was developed for this purpose!
(In contrast, when bread was cut with a knife, the sizes and shapes of the pieces were irregular.)
Was “breaking bread” a synonym for “dining together”? Not exactly. It was the ritual that preceded dining together. I say that because it seems to me unlikely that a fellowship group would get together, break bread (and drink wine?), and then not eat a meal together.
It is interesting to see that this ritual of distributing bread to all persons present and wine (ditto, to adults) before a (full) meal is preserved in orthodox Judaism. But there it is practiced within families as well as groups, and the breads are no longer circular and equally divided.