countervail vs counteract

countervail and counteract both are verbs.

Word	Noun	Adjective	Verb	Adverb
countervail	No	No	Yes	No
counteract	No	No	Yes	No

As verbs, countervail and counteract are synonyms defined as:

countervail and counteract: oppose and mitigate the effects of by contrary actions

Other synonyms of countervail include counterbalance, neutralize.

countervail (verb)	counteract (verb)
oppose and mitigate the effects of by contrary actions	act in opposition to
compensate for or counterbalance	destroy property or hinder normal operations
	oppose or check by a counteraction
	oppose and mitigate the effects of by contrary actions