Ballast

Any heavy substance, as stone, iron, etc., put into the hold to sink a vessel in the water to such a depth as to prevent capsizing.

Any heavy matter put into the car of a balloon to give it steadiness.

Gravel, broken stone, etc., laid in the bed of a railroad to make it firm and solid.

The larger solids, as broken stone or gravel, used in making concrete.

Fig.: That which gives, or helps to maintain, uprightness, steadiness, and security.

To steady, as a vessel, by putting heavy substances in the hold.

To fill in, as the bed of a railroad, with gravel, stone, etc., in order to make it firm and solid.

To keep steady; to steady, morally.