retrogress vs drop off

retrogress and drop off both are verbs.

Word	Noun	Adjective	Verb	Adverb
retrogress	No	No	Yes	No
drop off	No	No	Yes	No

As verbs, drop off is a hyponym of retrogress; that is, drop off is a word with a more specific, narrower meaning than retrogress:

Other hyponyms of retrogress include fall back, fall behind, recede.

retrogress (verb)	drop off (verb)
go back to bad behavior	change from a waking to a sleeping state
get worse or fall back to a previous condition	fall to a lower standard
	fall or diminish
	retreat
	remove (cargo, people, etc.) from and leave