sacred vs tabu

sacred is not a noun while tabu is a noun.

Word	Noun	Adjective	Verb	Adverb
sacred	No	Yes	No	No
tabu	Yes	Yes	No	No

sacred (noun)	tabu (noun)
	an inhibition or ban resulting from social custom or emotional aversion
	a prejudice (especially in Polynesia and other South Pacific islands) that prohibits the use or mention of something because of its sacred nature

sacred (adjective)	tabu (adjective)
concerned with religion or religious purposes	excluded from use or mention
(often followed by `to') devoted exclusively to a single use or purpose or person	forbidden to profane use especially in South Pacific islands
made or declared or believed to be holy; devoted to a deity or some religious ceremony or use
worthy of respect or dedication
worthy of religious veneration