tbh, I might ague here that the term probably is too engrained into modern culture and especially anime and manga culture this days for its original mythological meaning to be seen to strict. I think the definition of "defying the gods" is more suitable to the modern kind of devil race then...
I think he went out of the forest with 120, so the whole manga is around 110 years of his time... Na, it kinda makes sense. Maybe he forgot to count a decade or two but the rest makes sense.