tearing vs fierce

tearing is a noun but fierce is not a noun.

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

As adjectives, tearing and fierce are synonyms defined as:

tearing and fierce: marked by extreme intensity of emotions or convictions; inclined to react violently; fervid

Other synonyms of tearing include trigger-happy, vehement, violent.

tearing (noun)	fierce (noun)
shedding tears

tearing (adjective)	fierce (adjective)
marked by extreme intensity of emotions or convictions; inclined to react violently; fervid	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