Definition of: ballast

(bal′əst) noun
1. Any heavy substance, as sand, stone, etc., laid in the hold of a vessel or in the car of a balloon to steady it.
2. Gravel or broken stone laid down as a stabilizer for a railroad bed.
3. That which gives stability to character, morality, etc.
—v.t.
1. To provide or fill with ballast.
2. To steady with or as if with ballast; stabilize.
3. Obs. To weigh down. [<O Dan. barlast <bar bare, mere + last load]