Definition of fiercest:
(adj) :
Exceedingly violent, severe, ferocious, cruel or savage.
(adj) :
Resolute or strenuously active.
(adj) :
Threatening in appearance or demeanor.
(adj) :
(US, LGBTQ slang, fashion) Of exceptional quality, exhibiting boldness or chutzpah.
(adj) :
(slang, Ireland, rustic) Excellent, very good.
(adv) :
(slang, Ireland, rustic) Extremely; very.