How to Say "unlawfully" in Spanish
The Spanish word for “unlawfully” is “ilegalmente” — B1 level. This is a very common word in everyday Spanish.

Examples
Él cruzó la frontera ilegalmente.
He crossed the border illegally.
Muchas personas descargan películas ilegalmente de internet.
Many people download movies illegally from the internet.
La empresa obtuvo los documentos ilegalmente.
The company obtained the documents unlawfully.
The '-mente' Ending
In Spanish, adding '-mente' to the end of a feminine adjective (like 'ilegal') is just like adding '-ly' in English. It describes how an action is performed.
Adverbs Never Change
Unlike nouns or adjectives, 'ilegalmente' never changes to match gender or number. Whether one person or ten people act, the word stays exactly the same.
The Double 'L' Trap
Mistake: “illegaimente”
Correction: ilegalmente (In Spanish, 'illegal' only has one 'l' at the start, unlike the English spelling).
Incorrect Placement
Mistake: “Él ilegalmente cruzó.”
Correction: Él cruzó ilegalmente. (Usually, words that describe 'how' an action is done come right after the action word in Spanish).
Related Translations
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