1
general::
1. The office where seats for a play, concert, or other form of entertainment may be purchased, as in Tickets are available at the box office. It is so called because originally (17th century) it was the place for hiring a box, a special compartment of theater seats set aside for ladies. [Second half of 1700s] 2. The financial receipts from a performance; also, a show's relative success in attracting a paying audience. For example, You may not consider it great art, but this play is good box office. [c. 1900]
American Heritage Idioms
2
general::
noun BOX OFFICE + NOUN hit, success | receipts, takings Box office receipts for the film have hit $50 million. PREP. at a/the ~ Tickets are available at the box office. PHRASES do well/badly at the box office The musical has done very well at the box office (= a lot of tickets have been sold).
Oxford Collocations Dictionary