Longman Dictionary of Contemporary English
Wiktionary
n. 1 (label en countable film theater) A place where tickets are sold in a theatre/theater or cinema. 2 (label en uncountable by extension film) the total amount of money paid by people worldwide to watch a movie at cinemas/movie theaters.
WordNet
n. total admission receipts for an entertainment
the office where tickets of admission are sold [syn: ticket office, ticket booth]
Wikipedia
A box office is a place where tickets are sold to the public for admission to an event. Patrons may perform the transaction at a countertop, through a hole in a wall or window, or at a wicket.
By extension, the term is frequently used, especially in the context of the film industry, as a synonym for the amount of business a particular production, such as a film or theatre show, receives.
Box office business can be measured in terms of the number of tickets sold or the amount of money raised by ticket sales ( revenue). The projection and analysis of these earnings is very important for the creative industries and often a source of interest for fans. This is predominant in the Hollywood movie industry.
Usage examples of "box office".
But once we had left the hall and saw the line waiting outside the box office, our courage seeped away.
My guess was that two movies would tie for first place in the box office rankings this weekend.