close up vs dummy up

close up and dummy up both are verbs.

Word	Noun	Adjective	Verb	Adverb
close up	No	No	Yes	Yes
dummy up	No	No	Yes	No

As verbs, close up and dummy up are synonyms defined as:

Other synonyms of close up include be quiet, belt up, button up, clam up, keep mum, shut up.

close up (verb)	dummy up (verb)
refuse to talk or stop talking; fall silent	refuse to talk or stop talking; fall silent
block passage through	make a dummy of
unite or bring into contact or bring together the edges of
cease to operate or cause to cease operating

close up (adverb)	dummy up (adverb)
very close