Synonyms of prohibited

2 Syllables
vetoed, wildcat, banned, crooked, taboo, no-no, barred, shady
3 Syllables
contraband, refused, outlawed, verboten, proscribed, illicit, illegal, restricted, unlawful
4 Syllables
unlicensed, extralegal
5 Syllables
under-the-counter
6 Syllables
unconstitutional