Synaxis refers to the gathering for action at the beginning of a service; it is a name for the first part of the eucharistic service.
Here I want to suggest that the action of gathering at the very beginning of a service is worth some careful reflection. I have been in a few services lately where guests have been present. As the service has unfolded I have wondered whether the 'feel' of the service might have been improved if we had exchanged greetings at the beginning of a service. When this happens we are in fellowship through the service as friends rather than strangers.
Note that I have said 'exchange of greetings' rather than 'Exchange of (the) Peace'. The latter should always take place at its proper place between the Synaxis and the Eucharist proper. The former, I am suggesting, has a place in some situations, especially those where either the special character of the service or the special day in which the service takes place warrants it as guests are present.