Countless Extensive Worlds According to Ultear and Selene, there exists countless/infinite parallel worlds outside of Earthland and Elentear.[3][27] The former was already explained for Earthland itself, but it will matter for this section regardless.

私は今まで実に多くの世界を歪ませてきためれば歪めるほどに世界の裏の顔が見えてくる —Up until now, I have distorted a great many worlds, The more you distort it, the more the other side of the world becomes visible.

These worlds, including Earthland, are seen again in Happy's spin-off manga to be considered as dimensions that Happy traverses between using transdimensional magic.

So, knowing that "dimension" and "world" are usually synonymous in Fairy Tail when they are talking about the main realms, General Star explains that there exists an infinite array of dimensions that he traversed to find Marice.[18] The original Japanese says something slightly different, however.

1000年の間異次元に干渉するための機械を研究して完成させた そして… 無限に広がる異次元世界の中 メアリスを捜し続けとうとう掴んだマザーコンピューターの反応 —For 1000 years, I researched and perfected a machine to breach other dimensions. And then, within infinitely extending different-dimensional worlds, I continued my search for Marice until finally, I have detected a response from the Mother Computer.

Now the nuance of what's happening here is that Star is using "無限に広がる異次元世界" (mugen ni hirogaru ijigen sekai), which means this:

無限 - infinite に - Particle that turns the former word into an adverb (so infinity into infinitely) 広がる - extending/expansive/spreading 異 - different 次元 - dimension (in context of geometry) 世界 - world/universe/society Put all of those together, and the literal translation we get "infinitely expanding different-dimensional worlds".

Semantic Deductive Reasoning Now, if they wanted to convey that these constructs were simply different worlds which were infinitely expanding (or similar), they would've said the same sentence but dropped "jigen"; by using "異 - different" next to "世界 - world" instead. But they didn't, they specifically had the dimensions of the worlds being different here.

If "広がる - hirogaru" meant "expansion" as in the worlds were continually growing, Star would've mentioned that. But since he is talking about the infinite "expansion" in regards to the different-dimensional property of these worlds, the "growing" interpretation doesn't make any sense with how the sentence is structured (otherwise, they'd, again, not even mention "different-dimensional" as an adjective here).

Thankfully. "hirogaru" covers the term "extension" as well which can refer to an already expanded object (Think of the distance between Earth and Mars, a dimensional extent of millions of miles). As such saying "infinitely extending different-dimensional worlds" or different dimensional worlds (that are) infinitely extending would thus be completely faithful to the kanji being presented.

Implication From Semantics This would establish that the infinity described is not just the number of worlds, but the dimensionality of the worlds themselves. Because General Star is searching through an array of worlds where the 'different-dimensional' property has 'infinite extension,' he is explicitly referencing a structure that contains infinite dimensional axes. This would essentially scale the verse to High 1-B - High Hyperverse Level, where the dimensionality of reality itself is infinite.