impugner
/ɪmˈpjuːnər/
noun
- A person who attacks, criticizes, or challenges someone's character, motives, or the validity of something.
- The journalist became an impugner of the company's safety record after the accident.
- As a frequent impugner of government policies, she was known for her sharp questions.
- The impugner of the theory failed to provide any alternative explanation.