suck up vs suck

suck up is not a noun while suck is a noun.

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

As verbs, suck up and suck are synonyms defined as:

Other synonyms of suck up include absorb, draw, imbibe, soak up, sop up, take in, take up.

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

suck up (verb)	suck (verb)
try to gain favor by cringing or flattering	give suck to
take in, also metaphorically	draw into the mouth by creating a practical vacuum in the mouth
ingratiate oneself to; often with insincere behavior	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.