1) the quality or state of being ferocious; fierceness.
2) fierce, ravenous, relentless.
3) one's level of ferociousness.
The cougar entered the bar in a heightened state of ferocity.
Fero-City, as in a city of ferocity. Used to describe something overwhelmingly ferocious (savagely fierce) in every direction and dimension. Often used when 'fierce' just won't cut it.
May also be used as a noun (see examples)
That guy with the curled mohawk, antique scarf, and authentic china teacup was rather ferocity. Let's follow him to the ends of the Earth.
Much ferocity was had by all on the eve of the new year.