Illegal means forbidden by law. Illicit is wider — it covers anything forbidden by law, rule or custom, and often carries a hint of secrecy or disapproval. All illegal acts are illicit; not all illicit ones are illegal. An affair can be illicit without breaking any law.
The core difference
Illegal is a legal judgement: a statute forbids it. Illicit is broader and softer at the edges — it can mean against the law, but it also covers what is against the rules, against convention, or simply not openly done.
- An illegal parking spot. — a law says no
- An illicit affair. — no law broken, but concealed and disapproved of
- The illicit drug trade. — both at once
The test
Ask whether a court could rule on it. If the answer is yes, illegal is precise. If the objection is moral, social or institutional rather than legal, illicit is the word — and it brings a whiff of secrecy that illegal does not.
The neighbours
English has several words in this space and they are not interchangeable:
- illegal — against the law
- unlawful — not authorised by law; often used where something is void or improper rather than criminal
- illicit — against law, rule or custom, usually covertly
- illegitimate — not properly authorised or justified; also a historical term for children born outside marriage
In law, unlawful and illegal are often distinguished: an unlawful contract is unenforceable, while an illegal act is punishable. Outside law the two are used loosely.
Elicit, which is a different word entirely
Elicit is a verb meaning to draw something out — "to elicit a response". It sounds identical to illicit and means something unrelated, which makes it one of the commonest homophone errors in written English.
Frequently asked questions
Is illicit the same as illegal?
Not quite. Illegal means forbidden by law; illicit covers anything against law, rule or custom, often with a sense of secrecy. An illicit affair breaks no law.
What is the difference between illegal and unlawful?
In legal use, illegal usually means punishable while unlawful means not authorised — an unlawful contract is unenforceable rather than criminal. Outside law they are used loosely.
Illicit or elicit?
Elicit is a verb meaning to draw out — "elicit a response". Illicit is an adjective meaning forbidden. They are homophones with no shared meaning.