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)
see also:
ballasted; ballasting; ballasts
1
: to steady or equip with or as if with ballast
They ballast the canoe with large rocks.
2
: to fill in (something, such as a railroad bed) with ballast (see ballast entry 1 sense 3)
Cite this Entry
“Ballast.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/ballast. Accessed 3 Aug. 2026.
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