ballast.

1. Material or weight added to improve balance, stability, or loading.

2. Stone or similar material placed around and beneath railway sleepers to support and drain the track.

3. A device that limits or regulates current in an electrical load, especially certain lamps.

Use it for

Words that belong together

• water ballast
• ballast tank

On the page

They shifted water ballast to correct the ship's list.

The ballast tank emptied more slowly than the alarm predicted.

Usage notes

Primary category: sci-fi. Forms: Usually uncountable. Legacy lexical fields mirror sense 1 only. Use numbered sense fields for all meanings.