ballast
Concise Oxford English Dictionary © 2008 Oxford University Press:
ballast /ˈbaləst/
▶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.
– origin C16: prob. of Low Ger. or Scand. origin.
'ballast' also found in these Oxford entries:
