Satsang is the Indian practise of sitting together with a teacher who directs the attention past the mind to pure presence. People ask questions and the teacher keeps pointing their attention from the false identification with the impermanent self, to our true nature beyond thoughts and concepts.
Satsang is much broader though than the group session; any meeting where ones spirit is nourished and encouraged to shine is Satsang. So I consider practising Tai Chi with others to be our 'Satsang'. I love the way this term includes both the silent practise and the dialogue. In our practise both are also important in a session.
For more information on Satsang : http://www.satsangbhavan.net/