It often comes up in media that the first world war was of course not called the first world war when it happened, but they get hung up on the word "first". Time travel movie trope, "ah, this is the first world war!" - "what do you mean, first..."

But it also wasn't called a, or the, world war; it was the "great war" at the time. It only became the first world war when the other one happened, and historians tied them together as two sequential conflicts. The second one now made a new template, and because of that, we only even think of the possibility of another "world war". There were conflicts before both could quite well qualify as conflicts of a similar scope than the first one. The Seven Years War extended to north america, as did the napoleonic wars. Ancient wars spanned the width of the known world. They weren't called a world war because historians hadn't come up with that yet, and it was never applied retroactively, though it well could have been. It's all... wobbly.