Translation

自信のない / 内気な / 遠慮がちな

Meaning

Diffident means shy, hesitant, and lacking self-confidence, especially when speaking, asking, or presenting yourself. It is not the same as different. The learner trap is also mixing it up with confident, its near opposite.

Examples

• 彼女は優秀ですが、会議では少し遠慮がちです。
  She is talented but diffident in meetings.
• 彼は遠慮がちな笑みを浮かべて質問しました。
  He asked the question with a diffident smile.