breastfeed vs suck

breastfeed is not a noun while suck is a noun.

Word	Noun	Adjective	Verb	Adverb
breastfeed	No	No	Yes	No
suck	Yes	No	Yes	No

As verbs, breastfeed and suck are synonyms defined as:

Other synonyms of breastfeed include give suck, lactate, nurse, suckle, wet-nurse.

breastfeed (noun)	suck (noun)
	the act of sucking

breastfeed (verb)	suck (verb)
give suck to	give suck to
	draw into the mouth by creating a practical vacuum in the mouth
	take in, also metaphorically
	draw something in by or as if by a vacuum
	provide sexual gratification through oral stimulation
	be inadequate or objectionable
	attract by using an inexorable force, inducement, etc.