What is the difference between "illicit" and "illegal"? Are they just synonymous? Used in different contexts?

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    I'd suggest that in addition to the answers here, illicit also has the suggestion of clandestine. Thumping somebody would usually be illegal, but one wouldn't normally call that illicit. Commented Jul 6, 2011 at 18:48
  • 3
    And then there’s always unlawful, too.
    – tchrist
    Commented May 2, 2013 at 7:32
  • Illicit is something against the law, illegal is a sick bird. (@third grade joke) Commented Apr 27, 2017 at 15:46

6 Answers 6


Something illegal is forbidden by law: "It is illegal for motocyclists [sic] not to wear a crash helmet."

If a thing is illicit it is done by someone who knows that it is disallowed by law but that under different circumstances it could be legal: "The crew were involved in the illicit import of brandy"

(it is basically legal to import brandy but not the way they did it).

This is backed up by things like illicit sexual relationship. It's not wrong to have a sexual relationship normally, but it could be "wrong" if you are married, or not yet married, etc. illicit trade is another such example. It's not wrong to trade, unless you do it in the wrong way.

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    From your quote, it would seem that "illegal" and "illicit" mean the same thing. An illegal thing could also be legal under different circumstances. Illicit isn't alone on that point.
    – Daniel
    Commented Jul 6, 2011 at 13:22
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    An illicit thing isn't necessarily illegal. It may only be breaking social rules rather than legal ones.
    – user1579
    Commented Jul 6, 2011 at 16:35

An illegal action only breaks the law. An illicit action breaks ethical or moral standards (and probably the law as well).


  1. forbidden by law or statute.
  2. contrary to or forbidden by official rules, regulations, etc.


  1. not legally permitted or authorized; unlicensed; unlawful.
  2. disapproved of or not permitted for moral or ethical reasons.

As you see here, illicit can be used to mean illegal, but its second meaning makes all the difference. So if you want to preserve our precious English nuances, choose wisely!

  • Can something be illegal but not illicit? For example when something is not (or no longer) disapproved for moral reason, but is (still) forbidden by the law. Moral/ethical views change slowly, but laws often lag behind even more ;-) Commented Jul 6, 2011 at 13:33
  • @Joachim: Yes, if you go by the second definition of illicit.
    – Daniel
    Commented Jul 6, 2011 at 13:40
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    @Joachim: If it's very important to get across the fact that something is morally/ethically wrong, illicit might not be the word for you. You could try immoral, unethical, or some more explicit word.
    – Daniel
    Commented Jul 6, 2011 at 13:45
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    @Joachim: it is, for instance, illegal to eat mince pies on Christmas day (at least in England), but I don't think anyone could argue that it was immoral.
    – Andy F
    Commented Jul 6, 2011 at 14:04
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    @FumbleFingers: Those sound like the kind of excuses a mince pie muncher would come up with... To the tower with you!
    – Andy F
    Commented Jul 6, 2011 at 18:39

Illicit is forbidden by law, rules, custom or other set of principles. Illegal is forbidden only by law.

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    So something like "Henry, currently attending boarding school, made an illicit trip to town"? The trip isn't illegal itself, but is against the policy of the boarding school.
    – JAB
    Commented Jul 6, 2011 at 14:11
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    I like this answer best because it's brief and to the point. About the only relevant information missing is mention of the finer nuance as to why people ever use illicit rather than illegal. I think it's normally either because the writer wishes to emphasis that the debarring authority is something other than law, or to indicate less than total endorsement of the particular law involved. Commented Jul 6, 2011 at 17:21
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    Illicit might be used to highlight the moral quality of the act as opposed to its legal quality. In practical use it also often carries something of a connotation of secrecy that is absent in illegal.
    – Ryan Haber
    Commented Jul 6, 2011 at 19:06
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    @Ryan: I think your first point is strongly implied, if not explicitly stated, in my comment. But I like your second point. Actions described as illicit would rarely also be called overt, brazen, public, etc., but illegal actions may well be such. Commented Jul 7, 2011 at 15:52

Maybe the best ways to distinguish the two are their etymologies and their uses, which are related.

Illicit < Lat., licere, to permit.

Illegal < Lat., lex, a statutory law (as opposed to natural law, or what have you).

As noted above, illicit is a broader term that often includes a moral or ethical connotation, whereas illegal does not. It might be illegal to open the coolant reservoir on your air conditioner, but nobody thinks it is immoral. Likewise, adultery is often legal - or if illegal, not considered a criminal offense but only a matter of family law should a divorce be sought - but nobody really thinks of adultery as anything but an illicit affair.

The terms are used, relative to each other, differently in different contexts.

In canon law of the Catholic Church, the two words are synonymous, and are opposed to the term invalid. Validity, in such a distinction, has to do with reality, whereas liceity has only to do with permission and regulation. For instance, a layperson may not preach at Mass. Ask any of my friends and they will tell you how preachy I can be. The Church's law does not deny my ability (validity, you might say - what I can do) to preach - it only denies me permission (liceity or legality - what I may) to do so.

In purely legal matters, though, liceity/validity are often the same thing. If a contract is entered into illicitly, it is generally not going to be valid - for instance, most contracts entered into with minors do not have legal validity.

Lastly, in civic affairs, we very often understand there to be a gap in the law when that which is considered to be illicit (certain shady handling of money by politicians, for instance) is still legal.

  • "It might be illegal to open the coolant reservoir on your air conditioner, but nobody thinks it is immoral." @Ryan -- I, for one, think it's immoral (you are exposing your neighbors to a pollutant for your own benefit; even when that's legal, it's still wrong.) For a better example, how about smoking dope? Commented Jul 6, 2011 at 21:08
  • Whoa ho! We can get into an ethics conversation, and there certainly is a case to be made that individual use of narcotics causes social harm, but that is pretty far afield, Malvolio, from a board on English language and usage. I think my point was perfectly clear.
    – Ryan Haber
    Commented Jul 7, 2011 at 21:50

Imo, I will choose illicit over illegal when the fact that an act that is being carried out in secret is key to my message. I think that comes across stronger than merely calling the action illegal, even tho being illegal is likely to relegate the act "to the shadows." If I don't want to waste the readers' time making that conclusion, it's likely because I want to build upon that - and delve into the consequence of secrecy.


I’ve always seen illegal and illicit the same way as about 10 dictionaries Google showed me just now, except Cambridge and Collins.

That is, illicit has two different meanings: not legally permitted or authorized; unlicensed; unlawful and separately, disapproved of or not permitted for moral or ethical reasons.

I take that to confirm my long view that anything illegal is illicit but not everything illicit need be illegal.

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