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Synonyms

illegal

American  
[ih-lee-guhl] / ɪˈli gəl /

adjective

  1. forbidden by law or statute.

    Synonyms:
    unlicensed, illicit, illegitimate, unlawful
  2. contrary to or forbidden by official rules, regulations, etc..

    The referee ruled that it was an illegal forward pass.


noun

  1. Informal: Disparaging and Offensive. illegal alien.

illegal British  
/ ɪˈliːɡəl /

adjective

  1. forbidden by law; unlawful; illicit

  2. unauthorized or prohibited by a code of official or accepted rules

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

noun

  1. a person who has entered or attempted to enter a country illegally

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

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

  • illegality noun
  • illegally adverb

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:

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.

At the time, Bahraman had 5,000 Persian Bibles, which are illegal in Iran, stored in his own apartment.

From Los Angeles Times • Apr. 4, 2026

"Of course, until yesterday the prime minister was claiming that this leadership had brought order to the chaos of illegal subsidies," it said.

From Barron's • Apr. 3, 2026

The Forestry Commission, which carried out the investigation, said it was the highest ever fine imposed on a case of illegal tree felling by a court in England.

From BBC • Apr. 2, 2026

Oregon’s Worker Fraud Protection Act makes it illegal to “falsely impersonate” a union representative and imposes fines for infractions.

From The Wall Street Journal • Apr. 1, 2026

In typical American fashion, bold innovations and clever ideas to meet the demand for illegal alcohol would ultimately impact American life forever.

From "1919 The Year That Changed America" by Martin W. Sandler