I think poly is kind of an umbrella term right now for a lot of different kinds of "multiple partners" type relationships. I am ENM (ethically non-monogamous) but if you're not familiar with the term (and most people aren't) saying poly is much easier. It is a bit like saying LGBT and including all the things that fit under the umbrella but aren't lesbian, gay, bi or trans.
It's not a very good umbrella term, the term itself implies a relationship structure where an individual is in multiple, involved intimate relationships. A couple in an open relationship where one or both partners engage in dalliances doesn't fall under that umbrella.
It's posible to draw such clear line? Surely, it's rather easy to convince oneself you have all your relationships nicely compartmentalized..till reality does otherwise.
