fellate vs suck

fellate is not a noun while suck is a noun.

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

As verbs, fellate and suck are synonyms defined as:

Other synonyms of fellate include blow, go down on.

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

fellate (verb)	suck (verb)
provide sexual gratification through oral stimulation	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.