Synonyms of unauthorized

2 Syllables
wildcat, groundless, crooked, wrongful, no-no, dirty, bootleg, shady
3 Syllables
pirated, contraband, black-market, bootlegged, outlawed, illicit, illegal, offstage, unlawful
4 Syllables
unjustified, hole-and-corner, unlicensed, unwarranted, unapproved, extralegal, unofficial, unsanctioned, surreptitious
5 Syllables
under-the-counter
6 Syllables
illegitimate, unconstitutional