| ballast (def. 5a). |
[bal-uh
st] 
| 1. | Nautical. any heavy material carried temporarily or permanently in a vessel to provide desired draft and stability. |
| 2. | Aeronautics. something heavy, as bags of sand, placed in the car of a balloon for control of altitude and, less often, of attitude, or placed in an aircraft to control the position of the center of gravity. |
| 3. | anything that gives mental, moral, or political stability or steadiness: the ballast of a steady income. |
| 4. | gravel, broken stone, slag, etc., placed between and under the ties of a railroad to give stability, provide drainage, and distribute loads. |
| 5. | Electricity.
|
| 6. | to furnish with ballast: to ballast a ship. |
| 7. | to give steadiness to; keep steady: parental responsibilities that ballast a person. |
| 8. | in ballast, Nautical. carrying only ballast; carrying no cargo. |