ballast
Americannoun
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Nautical. any heavy material carried temporarily or permanently in a vessel to provide desired draft and stability.
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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.
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anything that gives mental, moral, or political stability or steadiness.
the ballast of a steady income.
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gravel, broken stone, slag, etc., placed between and under the ties of a railroad to give stability, provide drainage, and distribute loads.
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Electricity.
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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.
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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)
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to furnish with ballast.
to ballast a ship.
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to give steadiness to; keep steady.
parental responsibilities that ballast a person.
idioms
noun
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any dense heavy material, such as lead or iron pigs, used to stabilize a vessel, esp one that is not carrying cargo
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crushed rock, broken stone, etc, used for the foundation of a road or railway track
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coarse aggregate of sandy gravel, used in making concrete
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anything that provides stability or weight
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electronics a device for maintaining the current in a circuit
verb
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
Derived Forms
Inflected Forms
Nouns
Participles
Conjugated Forms
Present
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ballastsimple
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ballastssimple
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have ballastedperfect
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has ballastedperfect
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am ballastingprogressive
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are ballastingprogressive
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is ballastingprogressive
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have been ballastingperfect progressive
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has been ballastingperfect progressive
Past
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ballastedsimple
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had ballastedperfect
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was ballastingprogressive
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were ballastingprogressive
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had been ballastingperfect progressive
Future
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.
Vocabulary lists containing ballast
Words Every Pirate Should Know
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The Cay
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"La Vida Robot" and "Reading, Writing and... Recreation"
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Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
The cooling kit is not mandatory but any driver who chooses not to use it has to carry 5kg of ballast in their car to ensure he does not have a competitive advantage.
From BBC • Jun. 25, 2026
“Some ship-owners are going to be hesitant for now to ballast towards the Arabian Gulf, and in the meantime we need to hear from insurers,” Crosby says.
From The Wall Street Journal • Jun. 15, 2026
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
"On May 4, two unidentified aircraft struck the outer plate of the port-side ballast tank at the stern of the HMM Namu at roughly one-minute intervals, causing flames and smoke," he said.
From Barron's • May 10, 2026
Lee ran through the figures, double-checked them, and then released the last of his ballast.
From "The Subtle Knife" by Philip Pullman
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
