hush up vs whitewash

hush up is not a noun while whitewash is a noun.

Word	Noun	Adjective	Verb	Adverb
hush up	No	No	Yes	No
whitewash	Yes	No	Yes	No

As verbs, hush up and whitewash are synonyms defined as:

Other synonyms of hush up include gloss over, sleek over.

hush up (noun)	whitewash (noun)
	a specious or deceptive clearing that attempts to gloss over failings and defects
	wash consisting of lime and size in water; used for whitening walls and other surfaces
	a defeat in which the losing person or team fails to score

hush up (verb)	whitewash (verb)
cause to be quiet or not talk	exonerate by means of a perfunctory investigation or through biased presentation of data
cover up a misdemeanor, fault, or error	cover with whitewash
	cover up a misdemeanor, fault, or error