suffer vs decline

suffer is not a noun while decline is a noun.

Word	Noun	Adjective	Verb	Adverb
suffer	No	No	Yes	No
decline	Yes	No	Yes	No

As verbs, decline is a hypernym of suffer; that is, decline is a word with a broader meaning than suffer:

Other hypernyms of suffer include worsen.

As verbs, decline is a hypernym of suffer; that is, decline is a word with a broader meaning than suffer:

Other hypernyms of suffer include worsen.

suffer (noun)	decline (noun)
	a downward slope or bend
	a gradual decrease; as of stored charge or current
	change toward something smaller or lower
	a condition inferior to an earlier condition; a gradual falling off from a better state; decline

suffer (verb)	decline (verb)
be in pain	grow smaller
undergo (as of injuries and illnesses)	grow worse
feel unwell or uncomfortable	show unwillingness towards
get worse in quality	inflect for number, gender, case, etc.
be set at a disadvantage	go down
put up with something or somebody unpleasant	fall in value
experience (emotional) pain	not accept as true
feel physical pain
undergo or be subjected to
undergo or suffer
be given to