drop-off vs alteration

drop-off and alteration both are nouns.

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

As nouns, alteration is a hypernym of drop-off; that is, alteration is a word with a broader meaning than drop-off:

drop-off: a change downward
alteration: an event that occurs when something passes from one state or phase to another

Other hypernyms of drop-off include change, modification.

drop-off (noun)	alteration (noun)
a change downward	the act of revising or altering (involving reconsideration and modification)
a steep high face of rock	the act of making something different (as e.g. the size of a garment)
a noticeable deterioration in performance or quality	an event that occurs when something passes from one state or phase to another