A Box Office Bomb, or a flop, is a movie for which production and marketing cost greatly exceeds its gross revenue. It doesn't mean, however, that it merely made studios lose money - gross revenue doesn't equal studio profit . It means it lost a truly spectacular amount of money. On the other hand, most but not all box office bombs cost their studios money: gross revenue often doesn't include revenue from DVDs and whatnot (justified because the revenue from theaters is much easier to count), or (often) revenue from the world outside America; justified, because other countries don't actually exist. (Well, this can be justified since a movie has to be succesful in your home turf first rather than overseas)