merciless vs fierce

merciless and fierce both are adjectives.

Word	Noun	Adjective	Verb	Adverb
merciless	No	Yes	No	No
fierce	No	Yes	No	No

merciless (adjective)	fierce (adjective)
having or showing no mercy	marked by extreme intensity of emotions or convictions; inclined to react violently; fervid
	ruthless in competition
	violently agitated and turbulent
	marked by extreme and violent energy