Apart from being a major movie rental chain
(see writeups above),
the word blockbuster has three other meanings;
The earliest use of the word comes from
World War II, and was used to describe
a large aerial bomb, large enough
to lay an entire city block to waste.
Additionally, a blockbuster can mean a
real estate agent who sells a house
a house in a "white neighborhood"
to an unwanted minority, such as a
african-american family, thus
"busting" the block. As above, the
symbolic meaning is that the block
is destroyed, as the value of the
houses in the neighborhood are
expected to fall. This usage of the
word is not more or less extinct.
The third and by far most popular
sense is something that is
large, important or popular,
such as a movie, a play,
a piece of music or a book.