n. 25B6; adjective TABOO, censored, forbidden, banned, proscribed, prohibited, not to be spoken of, ineffable, unspeakable, unutterable, unprintable, off limits; informal no go.
UNMENTIONABLE
Meaning of UNMENTIONABLE in English
Concise Oxford thesaurus English vocabulary. Краткий оксфордский словарь английского языка тезаурус. 2012