Technically. Japan uses the classification of season a bit differently than the U.S. So does the U.K. I believe.
U.K. uses "series" like we use "season". My mom almost had a heart attack when there were commercials for the "Series Finale" of Doctor Who.
I noticed that in Japan as well, there never seems to be an official distinction between different "seasons". They seem to be divided into seasons sorta when they're brought over here to the States if they're really long, like Fairy Tail, but even those don't seem right. I usually go by opening/ending credit changes (one or two different ones constitute one "season" based on how frequently they change to me).
Then they're the things like Fairy Tail 2 that just came out. Basically it's just a continuation of Fairy Tail, like how "series" 7 of Doctor Who just continues from series 6, but Fairy Tail 2 feels like it is sorta treated like a sequel rather than a continuation. Yet at the same time it's still just Fairy Tail.
Dragonball -> Dragonball Z -> Dragonball GT seem more like "true sequels". Naruto Shippuden seems like it could also go into this category. I base Naruto on the time skip, so they're not starting exactly where they left off, even though it's continuing the story. If I understand correctly Fairy Tail 2 just starts where the first had to go on a hiatus. But I wonder why something like Naruto changes after it's time skip, when (I'm pretty sure) One Piece didn't change, and I know Fairy Tail didn't, even though the world became majorly different after the 7 year skip.
Oh well, I guess what it boils down to is I have my own classifications, and that works for me.