ferocity vs fierceness

ferocity and fierceness both are nouns.

Word	Noun	Adjective	Verb	Adverb
ferocity	Yes	No	No	No
fierceness	Yes	No	No	No

As nouns, ferocity and fierceness are synonyms defined as:

Other synonyms of ferocity include furiousness, fury, vehemence, violence, wildness.

ferocity (noun)	fierceness (noun)
the property of being wild or turbulent	the property of being wild or turbulent