Meaning of “illegal” in the English Dictionary

"illegal" in English

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uk /ɪˈliː.ɡəl/ us /ɪˈliː.ɡəl/

B2 not allowed by law:

a campaign to stop the illegal sale of cigarettes to children under 16
Prostitution is illegal in some countries.
It is illegal to drive a car that is not registered and insured.
Cocaine, LSD, and heroin are all illegal drugs/substances.

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adverb uk /ɪˈliː.ɡəl.i/ us /ɪˈliː.ɡəl.i/


They entered the country illegally.
an illegally parked car

illegalnoun [ C ]


(Definition of “illegal” from the Cambridge Advanced Learner’s Dictionary & Thesaurus © Cambridge University Press)

"illegal" in American English

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us /ɪˈli·ɡəl/

against the law:

Fireworks are illegal in many places.
illegal immigrant/alien

An illegal immigrant/alien is a person who has entered a country without government permission.

adverb us /ɪˈli·ɡə·li/

(Definition of “illegal” from the Cambridge Academic Content Dictionary © Cambridge University Press)

"illegal" in Business English

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uk /ɪˈliːɡəl/ us

LAW not allowed by law:

According to state law, smoking is illegal in all public buildings.
illegal (for sb) to do sth It is illegal for a company to force an employee into early retirement.
make sth illegal The new law will make it illegal to record phone conversations without consent.

IT used to describe a character (= letter, number, or symbol) that you cannot use in a particular place on a computer, because it may create problems:

The colon is the only illegal character for file and folder names.

Approximately 500,000 workers enter the country illegally each year.

(Definition of “illegal” from the Cambridge Business English Dictionary © Cambridge University Press)