gaudy vs tacky

gaudy is a noun but tacky is not a noun.

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

As adjectives, gaudy and tacky are synonyms defined as:

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

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

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