Definition of ballast
1
:a heavy substance (such as rocks or water) placed in such a way as to improve stability and control (as of the draft of a ship or the buoyancy of a balloon or submarine)
- tossed several tons of ballast overboard
2
:something that gives stability (as in character or conduct)
- She provided the ballast we needed during stressful times.
3
:gravel or broken stone laid in a railroad bed or used in making concrete
4
:a device used to provide the starting voltage or to stabilize the current in a circuit (as of a fluorescent lamp)
—
in ballast
of a ship
:having only ballast for a load
