1. to challenge or question the truth, validity, or integrity of something
Usage: past tense of impugn; formal

Examples

• The defense attorney impugned the witness’s credibility.
• His motives were impugned by political opponents.
• The scientist’s research methods were impugned by peer reviewers.
• She felt her reputation had been unfairly impugned.
• The journalist impugned the company’s environmental claims.
• Critics impugned the validity of the study’s conclusions.