- (nautical) Heavy material that is placed in the hold of a ship (or in the gondola of a balloon), to provide stability.
- (construction) A material, such as aggregate or precast concrete pavers, which employs its mass and the force of gravity to hold single-ply roof membranes in place.
- Coarse gravel or similar material laid to form a bed for roads or railroads, or in making concrete.
- (figuratively) That which gives, or helps to maintain, uprightness, steadiness, and security.
- (figuratively) Anything that steadies emotion or the mind.
- (countable, electronics) device used for stabilizing current in an electric circuit (e.g.in a tube lamp supply circuit)
- To stabilize or load a ship with ballast.
- To lay ballast on the bed of a railroad track.