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.
Related Words
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
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
Looking to grow your vocabulary? Check out this interactive, curated word list from our team of English language specialists at Vocabulary.com – one of over 17,000 lists we've built to help learners worldwide!
"A Natural Balance" and "In My Dreams"
Interested in learning more words like this one? Our team at Vocabulary.com has got you covered! You can review flashcards, quiz yourself, practice spelling, and more – and it's all completely free to use!
Fear and Loathing in Cleveland: Trump's RNC Acceptance Speech
Want to remember this word for good? Start your learning journey today with our library of interactive, themed word lists built by the experts at Vocabulary.com – we'll help you make the most of your study time!
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.
“Making it illegal and arresting people is not the way to solve this problem,” Bass said at the debate on KNBC-TV.
From Los Angeles Times • May 19, 2026
In April, two people smugglers were jailed in Cardiff for organising the illegal entry of hundreds of migrants, but little of the profits they made could be traced.
From BBC • May 18, 2026
It documents 55,018 illegal evictions, 38,876 illegal rent increases, 32,015 complaints about a reduction of services and 24,179 harassment cases.
From Los Angeles Times • May 18, 2026
Polymarket, which is based offshore but has attracted many American users, says it analyzes trading for signs of illegal conduct.
From The Wall Street Journal • May 17, 2026
Christopher had argued very hard and loud to be left alone, but his father said it was probably illegal.
From "Impossible Creatures" by Katherine Rundell
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.
