Yeah, I actually cited this back in like...page 2 or something.
As to whether or not I am deflecting or incapable of answering your question...a little from column A, a little from column B. I had it in my head that I was going to bring this up as rape being unnatural meaning unnatural to the standard of common (but obviously not universal; pretty sure there is no such thing actually) human morality. "Most of us don't therefore it can't be natural because it's not a primary drive" sort of thing but after consideration I realize I...well, I don't know. As you quoted on the dictionary, the 10th definition could fit to rapists in the sense that rape is natural, but then, definition 9: " Established by moral certainty or conviction" kinda works with me in saying that, based on established moral certainty or conviction, no, rape is not natural.
I guess I'm saying that on a moral level it's not natural.