球

1. Origins, structure, and basic meaning

• Structure: 球 (たま) is a single-character noun read たま for a ball or sphere.
• Basic usage: It refers to a pitch in baseball and to dirt rolled into a round solid form.

2. Common pitfalls and similar expressions

• An object in play and a geometric shape
  • Sports context favors “ball,” while emphasis on round three-dimensional form supports “sphere.”