The term 'magnum' is a Latin word meaning 'GREAT' or 'LARGE'. It is often used to refer to a LARGE-caliber handgun, such as the .44 Magnum. The term can also be used to refer to a LARGE bottle of wine or champagne, usually containing twice the amount of liquid as a standard bottle. In the crossword, the solution for the term 'magnum' is 'opus', which is a Latin word meaning 'work' or 'piece of art'. It is often used to refer to a musical composition or other artistic work.