Hmmm.
According to my Mormon upbringing, Jesus counseled us to love everyone, even our enemies. If we suppose that this counsel is both sound and realistic, then we should all love a lot of people, including those with whom we are slutty. Since polyamory is literally translated to mean "many loves," then those with whom we are slutty must certainly be in a polyamorous relationship with us. So, sluttiness must be a subset of poly. Raise your hand if you're following my logic. [sneaks tongue out of cheek]
Nobutseriously folks, I both realize that everyone is free to define any word however they see fit, and that a word with "love" in its translation will have fuzzy outlines no matter how hard we try to pin it down. Having said that, and FWIW, the conversations I've had on poly forums over the past six years have led me to believe that polyamory is generally defined as, "the state of being, willingness to be, or inclination to be, part of a romantically-connected group of more than two adults, with the full knowledge and consent of all the adults in the group." It's a working definition based on my experience so far, and as specific as I think it needs to be while still leaving room for interpretation.
I've long known that people disagree on what polyamory means, but this thread has taught me that the issue is more emotionally charged than I used to think.