Counterbalance

1. A counterpoise to balance the weight of anything, as of a drawbridge or a scale beam.
2. A mass of metal in one side of a driving wheel or fly wheel, to balance the weight of a crank pin, etc., on the opposite side of the wheel
3. To oppose with an equal weight or power; to counteract the power or effect of; to countervail; to equiponderate; to balance.
4. A weight, power, or agency, acting against or balancing another