annihilative vs withering

annihilative is not a noun while withering is a noun.

Word	Noun	Adjective	Verb	Adverb
annihilative	No	Yes	No	No
withering	Yes	Yes	No	No

As adjectives, annihilative and withering are synonyms defined as:

annihilative and withering: wreaking or capable of wreaking complete destruction

Other synonyms of annihilative include annihilating, devastating.

annihilative (noun)	withering (noun)
	any weakening or degeneration (especially through lack of use)

annihilative (adjective)	withering (adjective)
wreaking or capable of wreaking complete destruction	wreaking or capable of wreaking complete destruction
	making light of