Box Office Success is a term used to describe a movie, play, or other form of entertainment that has been successful in terms of ticket sales and revenue. A 'HIT' is a movie or show that has been successful in terms of ticket sales and revenue, while a 'SELLOUT' is a performance that has sold all of its tickets. Therefore, the crossword solutions for the term Box Office Success are 'HIT' and 'SELLOUT', which indicate that the movie or show has been successful in terms of ticket sales and revenue.