suck up vs cotton up

suck up and cotton up both are verbs.

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

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

suck up and cotton up: ingratiate oneself to; often with insincere behavior

Other synonyms of suck up include cozy up, play up, shine up, sidle up.

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