Definition

Yuri doesn't have the same history behind it as Yaoi does, so it doesn't have the same sort of complicated definitions. As far as I know, yuri isn't an acronym, and I really have no idea where it came from (though it does mean lily in Japanese). Yuri is an all-inclusive term for femalexfemale relationships. It can mean sex or no sex, though, more recently, the term shoujoai (girl love) has come to mean strictly romance between girls.

Explainations

There aren't the same seme/uke relationships in yuri as in yaoi. I suppose there *can* be a seme and uke, but they aren't called that. I think it's just assumed that they take turns. ^^;; So, the 'x' doesn't have the same exact meaning, but it is used to denote a romantic/sexual relationship of some sort.

Fandom (aka "what do a bunch of straight guys know about lesbian sex?")

Absolutely nothing. ^_~ But more on that later... Yuri has a much more diverse fanbase than yaoi. As for why that is, I'm not sure. First of all, there are the straight/bi guys, obviously. They like it for the titillation factor. A lot of yuri is written by guys, because they like lesbian sex (hey, nothing against them. Yaoi's often the same for girls). Then there are the straight girls. Surprisingly, there are some straight girls into yuri. But they put less emphasis on the sex (they're more than likely not to read a PWP just for the sake of it). They like it for the emotions involved, and the sweetness of the relationship. Sort of like, "Aw... Sakura and Tomoyo are so *cute* together!" Some even write shoujoai. Lastly, there are the lesbian/bi girls. They like it for same reason as both the two previous groups. ^_^ In other words, they *would* read a PWP just for the sake of it (Mmm...yuri PWP... *_*)! ^o^ But they also like the romance, and the emotions involved. :) In yuri fanfiction, especially in HarukaxMichiru fanficion, lesbian/bi writers are very prominent. As for gay guys...I'm not sure. Maybe they read because of the common bond they share with lesbians? o.o;;; Of course, none of that is set in stone. There are guy yuri fanfic writers who focus on romance (and when there is sex, they get it right). I find it sort of pointless to question every fan's preferences. If they like it, they read it. If they don't, they don't read it. It's just that simple. Now for a semi-rant on bad lesbian sex. Admittedly, guys aren't the only ones guilty of this, but they're in the majority (read an AsukaxRei fic lately?). It's also pretty prominent in doujinshi. The exploding female orgasm. It's not real, folks. It doesn't happen. Sure, we have fluid, and at orgasm a little more is produced, but it isn't projected anywhere. I wish this myth would just go away... And, btw, more than 80% of women don't orgasm from penetration alone, they need clitoral stimulation, too.