ballast

American  

[bal-uhst] / ˈbæl əst /

noun

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.

   1. Also called ballast resistor.  a device, often a resistor, that maintains the current in a circuit at a constant value by varying its resistance in order to counteract changes in voltage.

   2. a device that maintains the current through a fluorescent or mercury lamp at the desired constant value, sometimes also providing the necessary starting voltage and current.

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verb (used with object)

1. to furnish with ballast.

   to ballast a ship.

2. to give steadiness to; keep steady.

   parental responsibilities that ballast a person.

idioms

1. in ballast, carrying only ballast; carrying no cargo.

ballast British  

/ ˈbæləst /

noun

1. any dense heavy material, such as lead or iron pigs, used to stabilize a vessel, esp one that is not carrying cargo

2. crushed rock, broken stone, etc, used for the foundation of a road or railway track

3. coarse aggregate of sandy gravel, used in making concrete

4. anything that provides stability or weight

5. electronics a device for maintaining the current in a circuit

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verb

1. to give stability or weight to

Usage

What does ballast mean? In general, ballast means something that provides stability or weight. In a specific sense, it’s most commonly used to refer to heavy material used to stabilize a vessel, such as a ship, especially when it’s not carrying cargo. It also refers to the crushed rock used for the foundation of railroad tracks and paved roads. In electronics, ballast refers to a device that maintains the current in a circuit. Ballast can also be used as a verb meaning to provide a ship with a material for ballast. In a more general sense, it can mean to keep steady or give stability to, including in a metaphorical way. Ballast can also be used metaphorically as a noun, especially in the context of mental, emotional, political, or economic stability. Example: The ship’s ballast was improperly secured and caused the ship to list in the water.

Other Word Forms

• ballaster
  noun
• ballastic
  adjective
• overballast
  verb (used with object)
• subballast
  noun
• underballast
  verb (used with object)

Etymology

Origin of ballast

1450–1500; < Middle Low German, perhaps ultimately < Scandinavian; compare Old Danish, Old Swedish barlast, equivalent to bar bare ¹ + last load; see last ⁴

Explanation

A ballast is any heavy material that helps to make a ship or plane stable, including metaphorical ships like your mood. If you hate school, the thought of a weekend coming might be a ballast for your mood. Ballast comes from old ship terminology for cargo. It came to mean the weight of the cargo that prevents the ship from rocking around on the open seas. Any craft, ship or plane, needs ballast. A weight on the bottom of a rocket might act as ballast to help it glide straight. If you’re driving in snow in a tiny tin can car, you’ll need to ballast, or add weight, to prevent the wheels from sliding around.

Example Sentences

Of this, $4.6 billion would be allocated to an education “Rainy Day Fund” as ballast against future economic downturns.

From Los Angeles Times • May 14, 2026

Their models realized that government bonds are no longer providing ballast against equity crashes.

From MarketWatch • Apr. 16, 2026

“Government bonds and gold are not providing ballast as equities fall, and that’s because investors are demanding more compensation for the risk of holding long-term bonds given persistent inflation and high debt levels,” he added.

From Barron's • Mar. 17, 2026

If you’re not in the mood for a hulking sirloin — and if just creamed spinach and a frosted martini feel like insufficient ballast — skip the burger.

From Salon • Mar. 11, 2026

“So we’ll have the balloon right now,” said Lee, “and you can set some men to fill it. And I mean at once. And that includes food, and water, and ballast.’

From "The Subtle Knife" by Philip Pullman

Related Words

• equilibrium