(a.) Contrary to, or in violation of law; unlawful\; illicit; hence, immoral; as, an illegal act; illegal trade; illegal love.

aberrant abnormal abominable actionable against the law anarchic anarchistic anomic atrocious banned barred black-market bootleg chargeable contraband contrary to law criminal delinquent deviant disgraceful evil felonious flawed forbade forbid forbidden hardly the thing hot ignominious illegitimate illicit impermissible improper inappropriate incorrect indecorous inequitable infamous iniquitous interdicted irregular justiciable lawless nonconstitutional nonlegal nonlicit nonpermissible not done not permitted not the thing off limits off-base off-color out of bounds out-of-line outlaw outlawed prohibited proscribed punishable ruled out sacrilegious scandalous shameful shameless sinful taboo tabooed terrible triable unallowed unauthorized unbalanced unconstitutional under the ban under-the-counter under-the-table undeserved undue unequal unequitable uneven unfit unfitting unjust unlawful unlicensed unmeet unmerited unofficial unpermissible unrighteous unrightful unsanctioned unseemly unstatutory unsuitable untouchable unwarrantable unwarranted verboten vetoed wicked wrong wrongful