Noun tabu has 2 senses

• tabu(n = noun.cognition) taboo - a prejudice (especially in Polynesia and other South Pacific islands) that prohibits the use or mention of something because of its sacred nature; Array
is a kind of bias, preconception, prejudice

• tabu(n = noun.attribute) taboo - an inhibition or ban resulting from social custom or emotional aversion; Array
is a kind of inhibition

Adjective tabu has 2 senses

• tabu(s = adj.all) taboo - forbidden to profane use especially in South Pacific islands; Array
• tabu(s = adj.all) forbidden, out, prohibited, proscribed, taboo, verboten - excluded from use or mention; "forbidden fruit"; "in our house dancing and playing cards were out"; "a taboo subject"