A blockbuster is something hugely popular and successful, especially a movie, book, or product that attracts massive audiences and makes lots of money. When a movie becomes a blockbuster, theaters fill with crowds eager to see it, and everyone seems to be talking about it. Star Wars, Jurassic Park, and The Avengers are classic blockbusters that dominated theaters and captured people's imaginations.

We also use the word for books (Harry Potter was a publishing blockbuster), video games, or any product that becomes wildly successful. The opposite might be a “flop,” something that fails despite high expectations.

Blockbusters usually combine exciting action, compelling stories, and impressive special effects or production values. Studios invest heavily in blockbusters, hoping they'll earn back their money many times over. When something becomes a blockbuster, it doesn't just succeed: it becomes a cultural phenomenon that seems like everyone experiences together.