Counterpoise (noun)

1. A weight or force that balances another weight or force.
2. A weight or force used to balance another weight or force.

Origin:

Late 16th century: from french contrepoids, from contre- "against" + poids "weight".

Examples:

1. The counterpoise on the scale helped to balance the weight of the object being measured.
2. The counterpoise was adjusted to balance the weight of the crane.
3. The counterpoise was used to balance the load on the lever.
4. The counterpoise was necessary to keep the platform level.
5. The counterpoise helped to balance the weight of the pendulum.