fierce B2

/fɪɹs/ Very strong, violent, or intense.

feral C2+

/ˈfɛrəl/ in a wild state, especially after escaping from domestication

fierceness C2+

/ˈfɪrsnəs/ the quality of being violent, intense, or savage

ferity C2+

/ˈfɛrɪti/ the state of being wild, savage, or untamed

ferociousness C2+

/fəˈroʊʃəsnəs/ the quality of being fierce, savage, or violently intense