illicit meaning , definition , what is illicit : not allowed by laws or rules, or strongl...: Learn more. Legal Terms Dictionary illicit - Meaning in Law and Legal Documents, Examples and FAQs Illicit means something that is illegal or not allowed by law, like drug dealing or stealing. In normal language you would also say " illegal " instead of " illicit " Illicit usually refers to something that is not morally proper or acceptable . Illicit activities — like smuggling or counterfeiting — happen under the radar of the law. The adjective ' illicit ' has its etymology rooted in Latin. It is derived from the Latin word 'illicitus,' which combines 'in,' meaning 'not,' and 'licitus,' meaning 'lawful' or 'permitted.' In Latin, 'illicitus' referred to something that was not in accordance with established laws or regulations. ' Illicit ' entered the English language in the 16th century and is used to describe actions, behaviors, or activities that are prohibited, forbidden, or considered unlawful by established laws ...