[juliannamed]

The word Sangha refers to the Ariya Sangha as well, not just the Bhikkhu Sangha. It is possible for a lay person to be part of the Ariya Sangha see http://en.wikipedia.org/wiki/Sangha

I agree that referring to ones sitting group for example as a Sangha is very optimistic and cheapens the word. However I'm not convinced that the Bhikkhu Sangha is the "only authoritative Buddhist teaching organization", it may have been 2500 years ago but Buddhism has adapted and evolved since then.