belleisle, I understand first getting on the forums and not quite knowing where to start.
In my opinion, the man you described does seem to be having affairs with multiple women, which is not considered poly. One could call it swinging, although in either poly or swinging, one's partners are usually still aware of any sexual activity or relationships.
You indicate that he claims to care about his sex partners, but apparently not the wife he chose to build a life with, and I find that very sad.
People may define poly in sorts of ways, but I've learned that honesty and trust are the foundations of any relationship, including poly.
The suggestion to look for posts and stickies is a good one, enter in a keyword and see what you can find.
And please don't be afraid to ask questions. You are not required to do alot of research before proving to anyone that your question is worthy. Yes, it may have been asked many, many times before, but it's still a new question to you.
Neon: Some of us may be confident enough to know the text book definition of what poly is, but many people are unsure - which is what leads them to these forums. I'm not a custodian, just a member. I look at my presence on the forums as a way to seek out information and support I need. I also hope to share any experience and opinion I have so that I may help others. I'm a retail manager and if a customer came in looking for something I thought was obvious, I wouldn't say "Gawd, didn't you SEE the giant sign there?!" I would try to be polite, welcoming, and do my best to help without judging their level of understanding. Your response came off as rather harsh and not especially welcoming to a new member who is obviously unsure and seeking help. Whether or not she is asking on someone elses behalf is irrelevant, she's asking. Maybe you are fortunate enough to live in a community that fully understands what poly is, but most of us don't. And when someone want's to understand what poly is, for themselves, for someone else, or just for the sake of knowing, it's in our best interest to articulate our answers responsibly.