The term "opioid" has become a dirty word. "Synthetic" is also dirty. When putting them together you get something that is dirty but also confusing -- and probably intentionally so. There's no scientific reason to categorize a drug as a "synthetic opioid" or a "synthetic anything," as you will read here. To see how silly it is, let's perform the same exercise with antibiotics and see how that works out.
As if the government and media haven't screwed up the story of the so-called "opioid crisis" thoroughly enough, why not add some meaningless and confusing terms to the mix? That way, absolutely no one can know what the hell is going on. Let's take a look at the confusion. There's plenty of it.