kotow vs suck up

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

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

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

Other synonyms of kotow include bootlick, fawn, kowtow, toady, truckle.

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

kotow (verb)	suck up (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