1 : to rush in forcibly or violently
2 : (of a natural population) to undergo a sudden upsurge in numbers especially when natural ecological balances and checks are disturbed
3 : to become active or violent especially suddenly : erupt
Did You Know?
Irrupt and erupt have existed side-by-side since the former entered the English language in the 1800s (erupt had been a part of the language for over two centuries at that point). Both are descendants of the Latin verb rumpere, which means "to break," but irrupt has affixed to it the prefix ir- (in the sense "into") while erupt begins with the prefix e- (meaning "out"). So "to irrupt" was originally to rush in, and "to erupt" was to burst out. But it's sometimes hard to distinguish the precise direction of a violent rush, and irrupt came to be used as a synonym of erupt in the senses "to become active or violent especially suddenly" and "to break forth."
"Montaigne was attuned to the kind of 'involuntary' memory that would one day fascinate Proust: those blasts from the past that irrupt unexpectedly into the present, perhaps in response to a long-forgotten taste or smell." — Sarah Bakewell, How to Live, 2010
"Purple finches and pine siskins both are expected to irrupt southward due to poor cone crops in the Northeast and Canada." — James McCarthy, Plain Dealer (Cleveland, Ohio), 3 Oct. 2016
Test Your Vocabulary with M-W Quizzes
Test Your Vocabulary
Fill in the blanks to complete the name for the forcible entry of molten rock or magma into other rock formations: _ n _ ru _ _ on.VIEW THE ANSWER
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