ferociously vs frighteningly

ferociously

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

  • Intensely or extremely. 

frighteningly

adv
  • In a frightening or terrifying manner. 

  • Very; beyond usual expectation so as to cause surprise or concern. 

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