The Oxford Thesaurus An A-Z Dictionary of Synonyms - taboo adj.

1) tabu, anathema, forbidden, interdicted, off limits, out of bounds, verboten, proscribed, banned, prohibited, restricted, unmentionable, unspeakable; censored, censorable, unacceptable, rude, impolite, indecorous, dirty, explicit; outlawed, illegal, illicit, unlawful: Our holiday in Benidorm is a taboo subject in my house. Many people dislike hearing taboo language used on radio or television. --n. 2) tabu, anathema, interdict, interdiction, proscription, ban, prohibition, restriction: There is still a strict taboo against mentioning bodily functions in public. --v. 3) tabu, forbid, interdict, proscribe, ban, prohibit: The hotel taboos the sharing of a room by unmarried couples.