illegal
Americanadjective
-
forbidden by law or statute.
- Synonyms:
- unlicensed, illicit, illegitimate, unlawful
-
contrary to or forbidden by official rules, regulations, etc..
The referee ruled that it was an illegal forward pass.
noun
adjective
-
forbidden by law; unlawful; illicit
-
unauthorized or prohibited by a code of official or accepted rules
noun
Sensitive Note
See illegal alien.
Synonym Usage
Illegal, unlawful, illegitimate, illicit, criminal can all describe actions not in accord with law. Illegal refers most specifically to violations of statutes or, in organized athletics, codified rules: an illegal seizure of property; an illegal block ( in football ). Unlawful means not sanctioned by or according to law: an unlawful claim to the inheritance; to take unlawful advantage of the trading situation. Illegitimate means lacking legal or traditional right or rights: an illegitimate child; illegitimate use of privileged knowledge. Illicit, which originally meant simply “not permitted,” now most often applies to matters regulated by law with specific emphasis on the way things are carried out: illicit conversion of property; an illicit attempt to control the market. Criminal most often refers to violation of the statutes of penal as opposed to civil law. All felonies are criminal as are all crimes sometimes punishable by death such as murder, arson, and kidnapping: a criminal act.
Other Word Forms
Derived Forms
Etymology
Origin of illegal
From the Medieval Latin word illēgālis, dating back to 1620–30. See il- 2, legal
Compare meaning
How does illegal compare to similar and commonly confused words? Explore the most common comparisons:
Explanation
Something illegal is against the law or breaks the rules. If you're reading this in jail, you've probably done something illegal, and if you're not in jail, there's plenty of time to obey the law. You can use the adjective illegal to describe breaking the rules, as when you head-butt someone in a game. Acts that go against the law, such as robbing a bank, are also illegal. There is a wide range of things called illegal, from small acts to big ones, but no matter the seriousness, if it is against the law, it is illegal. This adjective also describes people who enter countries without official government approval, they are called "illegal immigrants" or "illegal aliens."
Vocabulary lists containing illegal
List 3
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Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
Police departments are also trying to educate the public before issuing citations or towing an illegal bike, but officials said it’s a challenge.
From Los Angeles Times • Jun. 10, 2026
It also announced that, for the first time, the UK's official guidance would "explicitly advise businesses against economic and financial activity in illegal settlements".
From BBC • Jun. 9, 2026
The wall is intended to curb illegal immigration and narcotics trafficking from Mexico, which have declined, according to official indicators.
From Barron's • Jun. 9, 2026
In written testimony, Glynn shared his experience hearing about young women performing illegal abortions when he was a freshman at the University of South Dakota in 1966.
From Salon • Jun. 8, 2026
Wrongful convictions and illegal trials involving young children are very common.
From "Just Mercy" by Bryan Stevenson
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
