suck up vs kotow

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

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

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

Other synonyms of suck up include bootlick, fawn, kowtow, toady, truckle.

suck up (noun)	kotow (noun)
	a former Chinese custom of touching the ground with the forehead as a sign of respect or submission

suck up (verb)	kotow (verb)
try to gain favor by cringing or flattering	try to gain favor by cringing or flattering
take in, also metaphorically
ingratiate oneself to; often with insincere behavior