counteract
Meaning: to neutralize, make ineffective
Usage: The antidote counteracted the effect of the poison.
mitigate
Meaning: to make less violent, alleviate
Usage: When I had an awful sore throat, only warm tea would mitigate the pain.
quell
Meaning: to control or diffuse a potentially explosive situation
Usage: The skilled leader deftly quelled the rebellion.
reconcile
Meaning: to return to harmony 2. to make consistent with existing ideas
Usage: Alou had to reconcile his skepticism about the existence of aliens with the fact that he was looking at a flying saucer.
resolve
Meaning: to find a solution; to decide firmly
Usage: The team resolved the problem before the final presentation.