ebb away vs ebb

ebb away is not a noun while ebb is a noun.

Word	Noun	Adjective	Verb	Adverb
ebb away	No	No	Yes	No
ebb	Yes	No	Yes	No

As verbs, ebb away and ebb are synonyms defined as:

Other synonyms of ebb away include ebb down, ebb off, ebb out.

ebb away (noun)	ebb (noun)
	the outward flow of the tide
	a gradual decline (in size or strength or power or number)

ebb away (verb)	ebb (verb)
flow back or recede	fall away or decline
	hem in fish with stakes and nets so as to prevent them from going back into the sea with the ebb
	flow back or recede