drop-off vs casualty

drop-off and casualty both are nouns.

Word	Noun	Adjective	Verb	Adverb
drop-off	Yes	No	No	No
casualty	Yes	No	No	No

As nouns, casualty is a hyponym of drop-off; that is, casualty is a word with a more specific, narrower meaning than drop-off:

Other hyponyms of drop-off include shrinkage, shrinking, sinking, attrition, rarefaction, dwindling, dwindling away, waning.

drop-off (noun)	casualty (noun)
a change downward	a decrease of military personnel or equipment
a steep high face of rock	an accident that causes someone to die
a noticeable deterioration in performance or quality	someone injured or killed in an accident
	someone injured or killed or captured or missing in a military engagement