Blockbuster, as applied to film or theatre, denotes a very popular or successful production. The entertainment industry use was originally theatrical slang referring to a particularly successful play, but is now used primarily by the film industry and the Pharmaceutical industry. The term ‘blockbuster’ in film generally speaks to the size of both the narrative and the scale of production. On the other hand, a ‘blockbuster’ drug generally implies a successfully marketed therapeutic drug.

Look it up at:
Google

Google Images
Wikepedia