tacky vs gaudy

tacky is not a noun while gaudy is a noun.

Word	Noun	Adjective	Verb	Adverb
tacky	No	Yes	No	No
gaudy	Yes	Yes	No	No

As adjectives, tacky and gaudy are synonyms defined as:

Other synonyms of tacky include brassy, cheap, flash, flashy, garish, gimcrack, loud, meretricious, tatty, tawdry, trashy.

tacky (noun)	gaudy (noun)
	(Britain) a celebratory reunion feast or entertainment held at a college

tacky (adjective)	gaudy (adjective)
tastelessly showy	(used especially of clothes) marked by conspicuous display
(of a glutinous liquid such as paint) not completely dried and slightly sticky to the touch	tastelessly showy