ballast

noun bal·last \ ˈba-ləst \

Updated on: 17 Apr 2018

Definition of ballast

1 : a heavy substance (such as rocks or water) placed in such a way as to improve stability and control (as of the draft of a ship or the buoyancy of a balloon or submarine)

tossed several tons of ballast overboard

2 : something that gives stability (as in character or conduct)

She provided the ballast we needed during stressful times.

3 : gravel or broken stone laid in a railroad bed or used in making concrete

4 : a device used to provide the starting voltage or to stabilize the current in a circuit (as of a fluorescent lamp)

— in ballast

of a ship : having only ballast for a load

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Recent Examples of ballast from the Web

Compressed air pushes water out of ballast tanks to increase the sub’s buoyancy until the upward force cracks the ice.

— david hambling, Popular Mechanics, "How the Navy Punches a Nuclear Sub Through Arctic Ice," 5 Apr. 2018
Nearly half of that will be for the maintenance of its rail, ties and ballast.

— andrea rumbaugh, Houston Chronicle, "BNSF to spend $375M to maintain, expand Texas railways," 16 Feb. 2018
The other 70 pounds is just filler material known as ballast.

— amy hall, sandiegouniontribune.com, "Growing season ahead depends on proper feeding," 7 Mar. 2018
The company is less cyclical and a good ballast to the auto dealerships that are part of the Lynch Companies.

— guy boulton, Milwaukee Journal Sentinel, "Custom specialty vehicles, from mobile command centers to trucks for Snap-on dealers, generate solid growth for LDV," 19 Jan. 2018
The species are native to Russia and Ukraine, and are believed to have arrived in the U.S. in the 1980s aboard ships that released ballast water into the Great Lakes.

— keith ridler, idahostatesman, "Invent a new way to kill off invasive mussels, and this $100,000 could be yours," 20 Feb. 2018
Their microscopic larvae, called veligers, reached the United States by way of the Great Lakes in the late 1980s, probably as stowaways inside a freighter's ballast tanks.

— OregonLive.com, "At Columbia River's doorstep, an uneasy lookout for invasive mussels," 10 Feb. 2018
The collision damaged some of the ship’s ballast and fuel tanks, and as a result the vessel dumped pollution into the pristine waters of the Coronation Gulf, far to the south of Resolute.

— chris mooney, Washington Post, "Scientists came to explore the fabled waters of the Arctic — but their work could also change its future.," 21 Dec. 2017
Unaccepted materials include: smoke detectors, ballasts, propane tanks, paint, household hazardous waste and appliances containing Freon, i.e. air conditioners, refrigerators, and dehumidifiers.

— Courant Community, "Community News For The West Hartford Edition," 26 Dec. 2017

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'ballast.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

Origin and Etymology of ballast

probably from Low German, of Scandinavian origin; akin to Danish & Swedish barlast ballast; perhaps akin to Old English bær bare & to Old English hlæst load, hladan to load — more at lade

NEW! Time Traveler

First Known Use: 15th century

in the meaning defined at sense 1

See Words from the same year