illegal
ih-LEE-guhl
Illegal (adjective) means Against the law; not authorised or permitted by legislation. Example: “It is illegal to drive without a valid licence.”
adjective
1
Against the law; not authorised or permitted by legislation.
"It is illegal to drive without a valid licence."
"The factory was fined for illegal dumping of waste."
"Parking on a double yellow line is illegal in most towns."
How to use illegal
Learner’s notesIn plain EnglishNot permitted by the law — the opposite of legal.
Common mistake
Don't confuse with "illicit," which can describe things that are socially disapproved of even if not technically criminal.
Easily confused with
Common pairings
illegal activity
illegal immigrant
declare illegal
Vocabulary Flow
Build your vocabulary from words like illegal.
Vocabulary Flow serves the next word, and the next — meaning, pronunciation and an example each time. Practice at your level, or learn English in your own language.
Start vocabulary practice
Word forms
- Plural
- illegals
- Comparative
- more illegal, illegaler
- Superlative
- most illegal, illegalest
Fill the gap
Can you complete this real example?
It is _____ to drive without a valid licence.
Etymology
Borrowed from French illégal, from Medieval Latin illegalis — "not" (il-) + "legal" (legalis).
Synonyms
View more →Antonyms
Related words
Rhymes for illegal
See all rhymes for illegal →Frequently asked questions
What does “illegal” mean?
The word “illegal” means against the law; not authorised or permitted by legislation. In plain terms, not permitted by the law — the opposite of legal.
How do you pronounce “illegal”?
“Illegal” is pronounced ih-LEE-guhl (/ɪˈli.ɡəl/ in IPA).
How do you use “illegal” in a sentence?
Here is “illegal” used in a sentence: “It is illegal to drive without a valid licence.”
What is another word for “illegal”?
Words with a similar meaning to “illegal” include illegal immigrant.
What part of speech is “illegal”?
“Illegal” is an adjective.
Where does the word “illegal” come from?
The word “illegal” comes from Medieval Latin. Borrowed from French illégal, from Medieval Latin illegalis — "not" (il-) + "legal" (legalis).
Is “illegal” a common word?
“Illegal” is a fairly common word in modern English, usually learned at around the A2 level.
What is the difference between illegal and illicit?
Illegal means specifically against the law — forbidden by legislation, like driving without a license. Illicit is broader: it covers anything forbidden by law, custom, or morality, and often carries a sense of secrecy or disapproval, as in an illicit affair. Everything illegal is illicit, but not everything illicit is strictly illegal.
What is the difference between illegal and unlawful?
The two overlap heavily and are often interchangeable, but there is a shade of difference. Illegal usually means expressly forbidden by a specific statute or criminal law. Unlawful is a touch broader, covering anything not permitted by law, including acts that break civil rules without being outright crimes. In everyday speech, most people treat them as synonyms.
What is the opposite of illegal?
The direct opposite is legal — allowed and recognized by law. Related words include "lawful," "permitted," and "authorized." Something legal complies with the rules and carries no penalty, whereas something illegal breaks them and can be punished. The pair marks the basic line between what the law allows and what it forbids.
Featured in
Vocabulary lists that include illegal:
