[ ih-lee-guhl ]
See synonyms for: illegalillegally on

  1. forbidden by law or statute.

  2. contrary to or forbidden by official rules, regulations, etc.: The referee ruled that it was an illegal forward pass.

  1. Informal: Disparaging and Offensive. illegal alien.

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Origin of illegal

From the Medieval Latin word illēgālis, dating back to 1620–30. See il-2, legal

synonym study For illegal

1, 2. 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.

usage note For illegal

3. See illegal alien.

Other words for illegal

Other words from illegal

  • il·le·gal·ly, adverb

Words that may be confused with illegal

  • illegal , illicit (see synonym study at the current entry)

Words Nearby illegal Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use illegal in a sentence

British Dictionary definitions for illegal


/ (ɪˈliːɡəl) /

  1. forbidden by law; unlawful; illicit

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

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

Derived forms of illegal

  • illegally, adverb
  • illegality, noun

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