The term 'athletic STADIUM' can be broken down into two crossword solutions: 'ARENA' (5 letters) and 'STADIUM' (7 letters). An ARENA is an enclosed area, often circular or oval-shaped, designed for spectator sports, concerts, or other events. It typically consists of a large open space surrounded by tiers of seating for spectators. A STADIUM, on the other hand, is a large structure with a roof and open sides, usually used for outdoor sports or other events. Stadiums are typically much larger than arenas and often have a running track around the perimeter. Both arenas and stadiums are used to host athletic events, such as football, soccer, basketball, and baseball games.