lessening vs attrition

lessening and attrition both are nouns.

Word	Noun	Adjective	Verb	Adverb
lessening	Yes	No	No	No
attrition	Yes	No	No	No

As nouns, attrition is a hyponym of lessening; that is, attrition is a word with a more specific, narrower meaning than lessening:

Other hyponyms of lessening include shrinkage, shrinking, casualty, sinking, rarefaction, dwindling, dwindling away, waning.

lessening (noun)	attrition (noun)
a change downward	the act of rubbing together; wearing something down by friction
	a wearing down to weaken or destroy
	sorrow for sin arising from fear of damnation
	the wearing down of rock particles by friction due to water or wind or ice
	erosion by friction