Translation

信じ込みやすさ / 軽信 / だまされやすさ

Meaning

Credulity is a tendency to believe things too easily, especially claims that are doubtful, exaggerated, or false. It is usually negative. Do not confuse it with credibility, which is the quality of being believable.

Examples

• 詐欺師は被害者の信じ込みやすさにつけ込みました。
  The scammer exploited the victim's credulity.
• そのうわさを信じるには驚くほどの軽信が必要でした。
  Believing the rumor required astonishing credulity.