bal·​last | \ˈba-ləst \

Definition of ballast 

(Entry 1 of 2)

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


ballasted; ballasting; ballasts

Definition of ballast (Entry 2 of 2)

transitive verb

1 : to steady or equip with or as if with ballast They ballast the canoe with large rocks.

2 : to fill in (something, such as a railroad bed) with ballast (see ballast entry 1 sense 3)

Examples of ballast in a Sentence

Recent Examples on the Web: Noun

The outage caused the drydock’s ballast tanks to fill rapidly, sinking the entire thing. Kyle Mizokami, Popular Mechanics, "Russia’s Hard-Luck Carrier Damaged in Shipyard Accident," 30 Oct. 2018 Clearest of all was Colin Greenwood, whose bass lines provided ballast – and cut the sharpest melodic path through the volatile arrangements. Greg Kot,, "Radiohead keeps things volatile at United Center," 7 July 2018 The Metra project includes removal and replacement of rails, ties, ballast, rubber panels and asphalt, said Metra spokeswoman Meg Thomas-Reile. Mary Wisniewski,, "Construction projects to close Ridgeland Avenue, I-294 ramps," 6 July 2018 That is why the classic 60-40 portfolio allocation ratio, with a higher allocation to stocks but a dose of bond ballast, makes a good deal of sense: it is tilted toward better returns but should perform better than stocks alone in troubled times. Richard Barley, WSJ, "Why Volatile Markets Are Good News for Careful Investors," 19 Apr. 2018 The crossing will be closed until July 20 and work will include the removal and replacement of rails, ties, ballast, rubber panels and asphalt, according to Metra. Mike Nolan, Daily Southtown, "Repairs to close Chicago Ridge railroad crossing," 9 July 2018 In his last four outings, Wood (5-5) has found ballast for his season while giving up only six earned runs in 242/3 innings. Andy Mccullough,, "Matt Kemp's five-hit, four-RBI effort leads Dodgers to 17-1 demolition of Pirates," 3 July 2018 Bassist Benny Trokan underlines the tunefulness with nimble lines that lope and chug, girding every song with a snappy precision and providing ballast for the strings that gild some of the tracks. Peter Margasak, Chicago Reader, "Montreal pop auteur Michael Rault summons the spirit of 70 AM pop radio on It’s a New Day Tonight," 29 June 2018 But one need only think there is a bit of inflation coming to think cash is a better ballast in a portfolio than bonds at the moment. James Mackintosh, WSJ, "Cashing In: Why Cash Should Be in Your Portfolio Again," 5 Apr. 2018

Recent Examples on the Web: Verb

Seawater ballasts help with stability and the horizontal surface is layered in solar panels and antennas. Bill Monroe,, "Oregon tag holders asked/required to report hunting, fishing results," 11 Jan. 2018 Seawater ballasts help with stability and the horizontal surface is layered in solar panels and bristles with antennas and a small wind generator. Bill Monroe,, "Local boat builder helps rower reach his ambition: Cross the Pacific Ocean," 5 Jan. 2018 Heritage-Crystal Clean contracted with Huston Electric to retrofit the light ballasts with LED fixtures. Carole Carlson, Post-Tribune, "Industry fines help fund upgrades at Gary schools," 23 Oct. 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.

See More

First Known Use of ballast


15th century, in the meaning defined at sense 1


1538, in the meaning defined at sense 1

History and Etymology for 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


see ballast entry 1

Keep scrolling for more

Learn More about ballast

Statistics for ballast

Last Updated

12 Nov 2018

Look-up Popularity

Time Traveler for ballast

The first known use of ballast was in the 15th century

See more words from the same century

Keep scrolling for more

More Definitions for ballast



English Language Learners Definition of ballast

: heavy material (such as rocks or water) that is put on a ship to make it steady or on a balloon to control its height in the air


bal·​last | \ˈba-ləst \

Kids Definition of ballast

1 : heavy material used to make a ship steady or to control the rising of a balloon

2 : gravel or broken stone laid in a foundation for a railroad or used in making concrete

Keep scrolling for more

Comments on ballast

What made you want to look up ballast? Please tell us where you read or heard it (including the quote, if possible).


something that serves to warn or remind

Get Word of the Day daily email!

Test Your Vocabulary

Autumn Words of the Day 2018

  • a-top-down-image-of-road-through-an-autumn-forest
  • Which is a synonym of fugacious?
Spell It

Can you spell these 10 commonly misspelled words?


Test Your Knowledge - and learn some interesting things along the way.


Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!