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. 2. To fill in, as the bed of a railroad, with gravel, stone, etc., in order to make it firm and solid. 3. To keep steady; to steady, morally. 'T is charity must ballast the heart. --Hammond. Ballasting \Bal"last*ing\, n. That which is used for steadying anything; ballast.