Translation

信用を失わせる / 疑わしくする / 誤りだと示す

Meaning

Discredit means to make people doubt that a claim, theory, witness, or source is true or reliable. It can also damage a person's reputation. The trap is confusing it with discount, which can mean reduce a price.

Examples

• 新しい証拠によって、その古い理論の信頼性は失われました。
  The new evidence discredited the old theory.
• その報告書は匿名の情報源の信用を落とそうとしました。
  The report tried to discredit the anonymous source.