真面目

1. Origins, structure, and basic meaning

• Structure: The fixed compound 真面目 (まじめ) denotes diligence or seriousness rather than its characters literally.
• Basic usage: 真面目な modifies a person, attitude, or discussion as diligent or serious, while 真面目に adverbially qualifies an action.

2. Common pitfalls and similar expressions

• な modification and に manner
  • The written characters should not be interpreted literally as true eyes.