impugn
im-PYOONverbMeaning to question someone’s honesty or the truth of a claim
Memory hook im-PUG-n: the PUG fights your word. Pip says he walked the dog twice today, but the pug barks, “Did NOT!” The pug impugns Pip’s story.
The visiting coach impugned the referee’s fairness.
In context Rather than argue with the scientist’s findings, the critic tried to impugn her motives, suggesting she had faked the results to win a prize.
Similar challenge, question, dispute, cast doubt on
Opposite support, defend, vouch for
From Latin impugnare, “to fight against, to attack”: in- (against) + pugnare (to fight).