[ 'baləst ]
■ noun
1》 a heavy substance, such as gravel or lead, placed in the bilge of a ship to ensure its stability.
↘a substance carried in an airship or on a hot-air balloon to stabilize it.
2》 gravel or coarse stone used to form the bed of a railway track or the substratum of a 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.
■ verb provide with ~.
Origin
C16: prob. of Low Ger. or Scand. origin.