dummy up vs close up

dummy up and close up both are verbs.

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

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

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

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

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