Poolroom Triangles, also known as billiard triangles, are triangular-shaped racks used to organize and store billiard balls. They are typically made of wood or plastic and come in various sizes. The term 'Poolroom Triangles' is derived from the fact that they are often found in pool halls and other places where billiards is played. RACKS, the five-letter solution to the crossword, is another word for Poolroom Triangles.