ballast

views updated May 14 2018

bal·last / ˈbaləst/ • n. 1. heavy material, such as gravel, sand, iron, or lead, placed low in a vessel to improve its stability. ∎  a substance of this type carried in an airship or on a hot-air balloon to stabilize it, and jettisoned when greater altitude is required. ∎ fig. something that gives stability or substance: the film is an entertaining comedy with some serious ideas thrown in for ballast.2. gravel or coarse stone used to form the bed of a railroad track or road. ∎  a mixture of coarse and fine aggregate for making concrete.3. a passive component used in an electric circuit to moderate changes in current.• v. [tr.] (usu. be ballasted) 1. give stability to (a ship) by putting a heavy substance in its bilge.2. form (the bed of a railroad line or road) with gravel or coarse stone.

ballast

views updated May 18 2018

ballast XVI. prob. f. LG., of uncert. orig. (perh. f. (i) bar BARE, mere or (ii) barm bosom, hull (of a ship) + last burden).