teaching: both the act of instructing others and the body of instruction that results.
This word covers the whole of teaching, from the doing of it to the thing done. In some verses it points to the activity, the act of instructing people; in others it points to the content, the actual body of instruction someone delivers. English keeps both under one roof too: we speak of a professor's teaching to mean "the way she teaches", and of the church's teaching to mean "what it holds". The Greek word works the same way, so a single word carries both the act and its product.
When the crowds are astonished at Jesus' teaching, the surprise is partly at what he says and partly at how he says it, with an authority the scribes lacked. That reaction shows why the two senses are hard to pull cleanly apart: the act and the content arrive together. The reader can usually tell which is in focus by the sentence around it. If the word takes a source (the teaching of the Pharisees, of Christ, of Balaam), the content is in view; if it describes what someone is doing, the act is in view.
Over the life of the early church the content sense hardened into something close to a fixed deposit:
- the apostles' teaching that the first believers devoted themselves to
- the pattern of teaching a convert was handed
- on the dark side, the false teachings that congregations were warned to reject
In these places the word names a recognizable body of belief and practice, identified by whose teaching it is.
Even so, the word never becomes a cold technical term. It keeps its lively edge of real instruction being given and received, so it should not be flattened into a dry synonym for a creed.