The Collaborative International Dictionary of English v.0.48:

Ballast \Bal"last\, v. t. [imp. & p. p. Ballasted; p. pr. &
   vb. n. Ballasting.]
   1. To steady, as a vessel, by putting heavy substances in the
      hold.
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   2. To fill in, as the bed of a railroad, with gravel, stone,
      etc., in order to make it firm and solid.
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   3. To keep steady; to steady, morally.
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            'T is charity must ballast the heart. --Hammond.
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