Definition of "fierce"

fierce

/fɪəs/

adjective
comparative fiercer or more fierce, superlative fiercest or most fierce
1. Exceedingly violent, severe, ferocious, cruel or savage.
2. Resolute or strenuously active.
  Quotations
  Yet his passion for her had grown fiercer than ever, and he swore to himself that he would win her back from her phantasies. She, one may believe, was ready enough to listen.
  1902, John Buchan, The Outgoing of the Tide
3. Threatening in appearance or demeanor.
4. (slang, Ireland, rustic) Excellent, very good.
5. (slang, US, LGBT, fashion) Of exceptional quality, exhibiting boldness or chutzpah.
adverb
not comparable
1. (slang, Ireland, rustic) Extremely; very.