ferociously vs fiercely

ferociously

adv
  • In a ferocious manner, particularly violent and aggressive. 

  • Intensely or extremely. 

fiercely

adv
  • In a fierce manner. 

  • extremely; to a large degree 

  • fiercely competitive 

How often have the words ferociously and fiercely occurred in a corpus of books? (source: Google Ngram Viewer )