fiercely
Concise Oxford English Dictionary © 2008 Oxford University Press:
fierce/fɪəs/
▶adjective (fiercer, fiercest) violent or aggressive; ferocious.
■ intense: fierce opposition.
■ (of a mechanism) having a powerful abruptness of action.
– phrases
something fierce N. Amer. informal to a great extent.
something fierce N. Amer. informal to a great extent.
– derivatives
fiercely adverb,
fierceness noun.
fiercely adverb,
fierceness noun.
– origin ME: from OFr. fiers ‘fierce, brave’, from L. ferus ‘untamed’.
'fiercely' also found in these Oxford entries:

