oppugn (v.)

• antagonize
• battle
• belie
• challenge
• clash
• collide
• conflict
• confute
• contest
• contradict
• contravene
• controvert
• counter
• counteract
• counterattack
• counterbalance
• countercheck
• counterpoise
• counterpose
• countervail
• cross
• deny
• fight
• gainsay
• negate
• offset
• oppose
• rebut
• reject
• resist
• traverse
• tug
• war