Countervail \Coun`ter*vail"\ (koun`t?r-v?l"), v. t. [imp. & p. p. Countervailed (-v?ld); p. pr. & vb. n. Countervailing.]

[OF. contrevaloir; contre (L. contra) + valoir to avail, fr. L. valere to be strong, avail. See Vallant.]

To act against with equal force, power, or effect; to thwart or overcome by such action; to furnish an equivalent to or for; to counterbalance; to compensate.

Upon balancing the account, the profit at last will hardly countervail the inconveniences that go allong with it. --L'Estrange.

Source: Webster's Revised Unabridged Dictionary (1913)