illegal

Etymology

Borrowed from French illégal, from Medieval Latin illegalis, from Latin legalis. In senses relating to immigration, via clipping from illegal alien or illegal immigrant.

adj

1. Contrary to or forbidden by law, especially criminal law.
   This is illegal, you know!
   Nearly 40 million people live in UK areas with illegal air pollution
   their illegal mining operations in Asia, Africa and elsewhere, are protected by officials and police paid to look the other way – and powerful customers in the construction industry who prefer not to ask too many questions.
   In all times the Princes in England have done ſomething illegal to get Money: But then came a Parliament and all was well, the People and the Prince kiſt and were Friends, and ſo things were quiet for a while. a. 1654, John Selden, “Money”, in Table-Talk, 3rd edition, London: Jacob Tonson, published 1716, page 74
   Imagine a country where children do nothing but play until they start compulsory schooling at age seven. Then, without exception, they attend comprehensives until the age of 16. Charging school fees is illegal, and so is sorting pupils into ability groups by streaming or setting. 2013-07-19, Peter Wilby, “Finland spreads word on schools”, in The Guardian Weekly, volume 189, number 6, page 30
2. Breaching certain enacted statutes of positive law; not lawful, not legal (cf. immoral, unethical)
3. Forbidden by established rules.
   Moving a pawn backward is an illegal move in chess.
4. (philately, of an issue printed for collectors) Totally fictitious, and often issued on behalf of a non-existent territory or country.
5. (of a person, sometimes offensive) Being or doing something illegally.
   illegal immigrant
   illegal logger
   illegal pilot
6. (chiefly US, sometimes offensive) Being an illegal immigrant; residing in a country illegally.

noun

1. (obsolete) An illegal act or technique.
   That whatſoever illegals hath been uſed againſt his friends and ſubjects, by impriſoning them without law, or impoſing fines upon their eſtates, be diſclaimed, and that perſons ſo committed be forthwith diſcharged. c. 1650, John Spalding, The History of the Troubles and Memorable Transactions in Scotland, from the Year 1624 to 1645, volume II, Aberdeen: T. Evans, published 1792, pages 72–73
2. (colloquial, in the plural, as illegals) Contraband, esp. illegal substances such as drugs.
   …I've got illegals in my bottom…! 2004, “Reapercussions”, in Dead Like Me, season 1, episode 4, spoken by Mason (Callum Blue)
   “Here’s what I could do,” Eve supposed. “I could slap your head against that wall, while I’m kicking your balls into your belly,” she added to the companion. “And after that, I can have you in restraints while I turn out your pockets. You’re carrying illegals. 2008, J. D. Robb [pseudonym; Nora Roberts], Strangers in Death, Penguin
3. (colloquial, offensive) An illegal immigrant.
4. (espionage) A spy working abroad illegally and undercover, without visible ties to his or her country’s authorities.
   Anna Chapman, whose glamorous appearance won her more publicity in the Western media than all the other illegals combined, was so successfully deceived by a US sting operation that she handed over her SVR laptop to an FBI agent posing as a Russian. 2012, Christopher Andrew, ‘Colder War’, Literary Review, number 399
   Traditionally, illegals have been extremely hard for counterintelligence agencies to find, but in a world of biometric data, facial recognition software and open source investigation possibilities, it has become harder for Russia to keep its illegals below the radar. 2022-08-26, Shaun Walker, “Socialite who charmed Nato staff in Naples was Russian spy, say investigators”, in The Guardian