The title doesn’t really mean anything in the series besides what @ragingloli and @uberbatman said. The creator, Hironobu Sakagucgi called it Final Fantasy specifically because that was going to be his last project. RPG’s weren’t popular much then, not over here anyways, so I guess he didn’t think it would catch on. But it did…rather well, at that.
But lo and behold lol. The games have changed from simple turn based combat driven games to…I don’t even know what the hell they’re about anymore, I pretty much stopped after number nine. (although I did try 10 and 12, hate both haha)
Keep in mind too, that most games all stand individually, and besides obvious trademarks and gameplay aspects, they never tie in to one another, besides a few, like the XIII series, X and X-2. Some of the games also take place in a kingdom called Ivalice, although they never have any relations with one another besides happening in the same land. (will stand corrected though, as I say I gave up on these quite a while back)
Rest assured though, the series is here to stay, at least for now. Not only that, but the FF formula was responsible for highly influencing what tons of role playing games were going follow from for years, in both gameplay and style. Fortunately, other developers have been doing their own thing instead of prescribing to FF. Although SE is kind of hurting at the moment, due to being a cash cow thinking it’s god, I don’t think we’re about to see the end of Final Fantasy anytime now…It’s a huge series with legions of fans.
PS; Sephiroth sucks.