1. Heavy material that is carried to improve stability or maintain proper trim, as on a ship, or to limit buoyancy, as on a balloon.
a. Coarse gravel or crushed rock laid to form a bed for roads or railroads.
b. The gravel ingredient of concrete.
3. Something that gives stability, especially in character.
tr.v. bal·last·ed, bal·last·ing, bal·lasts
1. To stabilize or provide with ballast.
2. To fill (a railroad bed) with or as if with ballast.
[Perhaps from Old Swedish or Old Danish barlast : bar, mere, bare; see bhoso- in the Appendix of Indo-European roots + last, load.]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.