The question of is unresisted a word? Are you saying that it's likely to become a word in time? I think that's very possible.
Ahaha, that would be awesome if that's what he meant! That's an answer to any type of question such as that.
I was wondering if it is, Time that this sentence is referencing, the one enemy of us all... "(name) what is the one enemy all dragons have, the one thing in this entire world that can effortlessly kill us all?”
That's an awesome guess, but no. It's actually the antagonist he's referring to. Honestly I didn't even think of time as being a possible answer. 2 points for thinking outside the box!