歯車

1. Origins, structure, and basic meaning

• Structure: Spelling: 歯車. Reading: はぐるま. Core meaning: gear; cog in a machine.
• Basic usage: Representative examples: 時計の小さな歯車に油を一滴差した / 組織の歯車として働くだけでは満足できなかった.

2. Common pitfalls and similar expressions

• Mechanical gear and organizational cog
  • It can mean a physical gear in a clock or figuratively a person performing a fixed function in an organization. The latter use, 組織の歯車, can suggest replaceability within the system.