IMPUGN

impugn: to assail or attack by words or arguments; to gainsay; oppose as false

Example: Even though it is nowhere alleged that disclosures of sinful activity by priests impugn the integrity of the entire ministry, that nevertheless is the passing legacy of the current scandals. [Reference: William F. Buckley Jr., "The House of Disillusion", National Review , May 14, 2002]

TRUCULENT

truculent:

- fierce; savage
- cruel; ruthless

Example: The danger comes if there becomes this sense that they are being truculent for the sake of being truculent. [Reference: NYTIMES.COM, THE NATION: CALCULUS; Perks and Perils of a Heavy Gavel, ADAM NAGOURNEY Published: March 25, 2007]