That's not quite the way I'd like to think of the word. I think it requires not merely a one-sided attraction, but also a failure on the part of the attracted party to recognize that one-sidedness. I agree that this doesn't require intentional manipulation on the part of the attracteee -- it can happen because of that, but it can also happen because said party isn't sure what they want, because they don't communicate what they want clearly, because they don't realize anyone's attracted to them, because the attracted party doesn't listen clearly, because the attracted party is deluding themselves, or for about a dozen different reasons. I've been in the position of being attracted to someone, but fully understanding that they didn't return that attraction and there was no reason to think they ever would, and I wouldn't call that situation "friendzoning".

That's just how I'd like the word to be used, though. I think, based on actual usage, that Arcantium gave a "good definition", and its the term itself as bad. I feel like a solid majority of the time, at least, "friendzone" is used in a very negative sense by men who feel entitled to have sex with the women they're attracted to.