Longman Dictionary of Contemporary English
illegal immigrant
noun
EXAMPLES FROM CORPUS
▪ I was warned before I left not to do anything silly, like becoming an illegal immigrant, a runaway.
Wiktionary
illegal immigrant
n. (context countable sometimes offensive English) Someone who has immigrated into a country by bypassing customs and immigration controls.
Usage examples of "illegal immigrant".
An illegal immigrant gave birth to a baby girl in the back of a Border Patrol van.
The victims are always Asian teenagers: we've just learned they're from illegal immigrant families who refused to put them into prostitution.
By the time they had persuaded the Oxford constabulary that Leovinus was not an illegal immigrant (even though technically speaking he was) it was well after half past one o'clock.