illicit

adjective

il·​lic·​it (ˌ)i(l)-ˈli-sət 

1

: not permitted : unlawful, illegal

illicit drugs/substances

illicit profits

2

: involving activities that are not considered morally acceptable

illicit sex

… particularly because she was suspected of having illicit affairs.

—David S. Reynolds

illicitly adverb

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Illicit and Elicit

Illicit, while not exactly an everyday word, is far more common than its antonym, licit ("not forbidden by law, permissible"). Perhaps this is a function of our oft-noted fascination with bad behavior and boredom with rectitude. In any case, illicit may be used of behavior that is either unlawful or immoral. These categories frequently overlap, but they are not always synonymous, as some unlawful activities (illicit cigarette smoking) may not be considered immoral, while some immoral activities (an illicit affair) are not illegal. Illicit is occasionally confused with elicit because of the similarity in their pronunciations, but the two words have decidedly different meanings and functions: in contemporary English, elicit is a verb meaning "to get (a response, information, etc.) from someone," while illicit appears solely as an adjective.

Synonyms of illicit

• illegal
• unlawful
• criminal

Examples of illicit in a Sentence

The wedding is mounted in traditional Punjabi style, but underneath the formal fanfare simmer dysfunctional-family tensions, deep dark secrets, … and illicit affairs. —David Ansen, Newsweek, 4 Mar. 2002

"Thank you, Lieutenant," she said, bowing her head, just as she might in everyday, civilian life, and I felt suddenly illicit in her presence, as though we'd slipped out of sight of our chaperons … —Chang-rae Lee, A Gesture Life, 1999

The companies that carry cellular … have adopted a number of monitoring techniques to detect illicit calls … —Paul Wallich, Scientific American, March 1994

He was arrested for selling illicit copies of the software.

She had an illicit affair with her boss.

Recent Examples on the Web

So far, the most plausible driver of recent declines in overdose deaths is a change in the illicit drug supply. — J. Travis Donahoe, STAT, 23 Oct. 2026

But how and through whom the money flowed into the Alpha account revealed that it was intended to remain secret, more akin to a covert and illicit scheme, given that it was managed in part by a senior advisor to the president of the United States. — Matthew Cole, Vanity Fair, 22 Oct. 2026

To be fair, some British ships were engaged in illicit trade in the Spanish colonies. — Encyclopedia Britannica, 20 Oct. 2026

The drug is not approved for medical use and has been detected in illicit drugs and counterfeit pills. — Melissa Rudy, FOXNews.com, 20 Oct. 2026

Word History

Etymology

Latin illicitus, from in- + licitus lawful — more at licit

First Known Use

1623, in the meaning defined at sense 1

Rhymes for illicit

• complicit
• elicit
• explicit
• implicit
• solicit
• licit

Kids Definition

illicit

adjective

il·​lic·​it (ˈ)il-ˈ(l)is-ət 

: illegal

illicit drug traffic

illicitly adverb

Legal Definition

illicit

adjective

il·​lic·​it il-ˈli-sət 

: not permitted : unlawful

an illicit motive to defeat or evade the taxes

—In re Haas, 48 F.3d 1153 (1995)