29
illegal(adjective, law, criminal, legal, illegal)
28
unlawful(adjective, law, right, irregular, unwarranted)
20
illegitimate(adjective, law, irregular, unwarranted, legal)
15
criminal(adjective, wrong, irregular, unwarranted, legal)
13
wrong(adjective, dishonest, immoral, legal, illegal)
12
felonious(adjective, irregular, unwarranted, criminal, legal)
12
prohibited(adjective, legal, forbidden, illegality)
12
unauthorized(adjective, legal, illegal, forbidden, undueness)
11
outlawed(adjective, law, irregular, unwarranted, criminal)
11
lawless(adjective, law, irregular, unwarranted, criminal)
10
wrongful(adjective, law, evil, legal, illegal)
10
forbidden(verb, adjective, illegal)
9
improper(adjective, dishonest, legal, illegal, illegitimate)
9
unlicensed(adjective, irregular, unwarranted, criminal, legal)
8
crooked(adjective, irregular, unwarranted, criminal, legal)
8
outlaw
7
actionable(adjective, illegal, illegality)
7
banned
7
verboten(adjective, illegal)
6
adulterous(adjective, legal, unfaithful, forbidden)
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APASmart Define. (2015). illicit thesaurus. Retrieved September 20, 2026, from https://smartdefine.org/illicit/thesaurus/synonyms
ChicagoSmart Define. 2015. "illicit thesaurus" https://smartdefine.org/illicit/thesaurus/synonyms (accessed September 20, 2026).
HarvardSmart Define 2015, illicit thesaurus, Smart Define, viewed 20 September, 2026, <https://smartdefine.org/illicit/thesaurus/synonyms>.
MLASmart Define. "illicit thesaurus" 13 April 2015. Web. 20 September 2026. <https://smartdefine.org/illicit/thesaurus/synonyms>