- anything heavy carried in a ship, aircraft, or vehicle to give stability or in a balloon or airship to help control altitude
- anything giving stability and firmness to character, human relations, etc.
- crushed rock or gravel, as that placed between and below railroad ties
- an electrical device used to supply and regulate electricity in fluorescent lamps, mercury-vapor lamps, etc.
Origin of ballastLow German from Middle Dutch from bal, bad, useless (akin to Old English bealu, bale) + last, a load
- to furnish with ballast; stabilize
- to fill in (a railroad bed) with ballast