Countervail

v. t. [imp. & p. p. COUNTER-VAILED; p. pr. & vb. n. COUNTERVAILING.] [counter and Lat. valere, to be strong, to avail; O. Fr. contrevaloir, Pr. contravaler, It. contravvalere.] To act against with equal force, power, or effect; to thwart or overcome by such action; to furnish an equivalent to or for; to equal; to balance; to compensate.

We are to compute, that upon balancing the account, the profit at last will hardly countervail the inconveniences that go along with it. L'Estrange.

n. Power or value sufficient to obviate any effect; equal weight, strength, or value; compensation; requital. South.