From
American Heritage Dictionary of the English Language, 5th Edition
From Frenchillicite, from Latinillicitus, from in- 'not' + licet (“it is allowed”)
From
Wiktionary
Illicit Sentence Examples
As a port it was notorious for its smuggling and illicit trade.
An important consequence of thus giving the study of primitive religion the wide scope of a comparative hierology is that magic is no longer divorced from religion, since the sacred will now be found to be coextensive with the magicoreligious, that largely undifferentiated plasm out of which religion and magic slowly take separate shape as society comes more and more to contrast legitimate with illicit modes of dealing with the sacred.
When the source of the name was forgotten its meaning was not unnaturally misinterpreted, and gained for Gawain the reputation of a facile morality, which was exaggerated by the pious compilers of the later Grail romances into persistent and aggravated wrong-doing; at the same time it is to be noted that Gawain is never like Tristan and Lancelot, the hero of an illicit connexion maintained under circumstances of falsehood and treachery.
In the 18th century land grants and illicit trade led to serious disturbances.