Q From Martin Jones: What is the derivation of blockbuster?
A Having just sat through the latest Harry Potter and Lord of the Rings filmic episodes, each of which seemed to be about nine hours long, I begin to understand the deepest meaning of this term, though in my case by the end of each it wasn’t the block that was busting.
The first blockbusters were much more serious and deadly: large bombs developed in the early years of World War Two by the Royal Air Force. The first examples, from April 1941 onwards, weighed 4000 pounds (1814kg) and were carried by Wellington and Lancaster bombers on raids into Germany. They were called block busters supposedly because they were capable of destroying a whole block at one time. (Block here has the more common British sense of a large single building subdivided into separate rooms, flats or offices rather than the usual American sense, as in city block, of an assemblage of buildings enclosed by streets.)
It was attached to books, plays or films with a figuratively similar explosive force only after the War — the first example I can find is from 1957.