noun
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
• figurative something that gives stability or substance
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
