When something is forbidden , it's not allowed. You were forbidden to use your father's computer but you did it anyway — and that's why you're grounded. Synonyms for FORBIDDEN : prohibited, banned, outlawed, illegal, barred, taboo, improper, unauthorized; Antonyms of FORBIDDEN : permissible, permitted, allowable ... Learn the meaning and usage of the word forbidden , which can be an adjective or a past participle of forbid. Find synonyms, translations, and related terms for forbidden in different contexts and languages. Learn the meaning and usage of the word forbidden , which means not allowed or prohibited. Find synonyms, pronunciation, grammar, and examples of forbidden in sentences and idioms.