Illegal: Definition, Usage & Common Errors

Meaning 1：against the law (illegal)

illegal 🔊

/ɪˈliːɡl/

adj.

Not allowed by the rules or laws of a country or organization.

Illegal definition illustrated by a customs officer inspecting prohibited items in a suitcase

against the law 🔊

➕

/əˈɡenst ðə lɔː/

adj.

Describes something that is forbidden or prohibited by official rules or statutes.

📁 Category：Laws & Regulations 🔖 Level：Elementary

📘 Details & Usage

📖 Root Explanation

From Latin 'in-' (not) + 'legalis' (lawful).

💡 Mnemonic

Think of 'ill' (sick) + 'legal'. An 'ill' (bad) action is not 'legal'.

📖 Example

The customs officer found the plants and declared them illegal because they had no entry documents. 🔊 The customs officer found the plants and declared them against the law because they had no entry documents.

🔗 Collocations

illegal activity – An action that breaks the law.

illegal immigrant – A person who enters or lives in a country without legal permission.

illegal substance – A drug whose possession or use is prohibited by law.

🔄 Synonyms

unlawful (adj.) – Not conforming to, permitted by, or recognized by law or rules.

illicit (adj.) – Forbidden by law, rules, or custom.

criminal (adj.) – Relating to or involving crime.

🚫 Antonyms

legal (adj.) – Permitted by law.

lawful (adj.) – Conforming to, permitted by, or recognized by law.

legitimate (adj.) – Conforming to the law or to rules.

🌱 Derivatives

illegality (n.) – The state of being illegal; an illegal act.

📖 Cultural Story

Derived from the Latin 'illegālis', combining the negative prefix 'in-' (which changes to 'il-' before 'l') with 'lēgālis' (pertaining to law). English adopted it via Old French 'illégal'. It reflects a core legal distinction in all societies governed by written codes.