slack·​en | \ ˈsla-kən How to pronounce slacken (audio) \
slackened; slackening\ ˈsla-​kᵊn-​iŋ How to pronounce slackening (audio) \

Definition of slacken

transitive verb

1 : to make less active : slow up slacken speed at a crossing
2 : to make slack (as by lessening tension or firmness) slacken sail

intransitive verb

1 : to become slack or slow or negligent : slow down
2 : to become less active : slack

Keep scrolling for more

Synonyms & Antonyms for slacken


ease, loosen, relax, slack


strain, stretch, tense, tension, tighten

Visit the Thesaurus for More 

Choose the Right Synonym for slacken

delay, retard, slow, slacken, detain mean to cause to be late or behind in movement or progress. delay implies a holding back, usually by interference, from completion or arrival. bad weather delayed our arrival retard suggests reduction of speed without actual stopping. language barriers retarded their progress slow and slacken also imply a reduction of speed, slow often suggesting deliberate intention medication slowed the patient's heart rate , slacken an easing up or relaxing of power or effort. on hot days runners slacken their pace detain implies a holding back beyond a reasonable or appointed time. unexpected business had detained her

Examples of slacken in a Sentence

Sales show no sign of slackening. As he began to relax, his grip on the steering wheel slackened. The captain ordered us to slacken the sails.
See More

Recent Examples on the Web

This year could be different, after economic growth in 2018 slackened to its slowest pace since 1990 and annual auto sales fell for the first time since that same year. Kevin Kingsbury, WSJ, "China’s Slowdown Is a Drag for Fuel Refiners," 23 Jan. 2019 Businesses are feeling the chill from the slowdown and trade tensions with the U.S. Earnings at Chinese industrial companies fell in November for the first time in nearly three years on the back of slackening demand. Wsj Graphics, WSJ, "Apple Warning: Seven Charts That Show the Pressure on China’s Consumers," 2 Jan. 2019 Still, there have been signs of slackening demand even there, with several potential issuers canceling sales of loans and investors negotiating for better terms than in previous months. Sam Goldfarb, WSJ, "Oil’s Swings Hit Junk Bonds, Prompting Fresh Debt-Market Concerns," 3 Dec. 2018 Only one Wall Street executive was sent to jail for the Crash of 2008, but a great many had to be defended, and the pace hasn’t slackened since. James Atlas, Town & Country, "The Year of the Celebrity Super Lawyer," 3 Dec. 2018 In fact, the US childbirth rate just reached a 30-year low in 2017, a trend that doesn’t appear to be slackening., "17 survival skills for modern adults," 7 July 2018 Confidence: High Tomorrow night: Winds slacken as high pressure overtakes the region. Brian Jackson, Washington Post, "D.C.-area forecast: A soggy, cold Super Bowl Sunday with patchy ice," 4 Feb. 2018 Once demand for crab feasts slackens, picking houses become important buyers of any of those undersized crustaceans. Scott Dance,, "After July Fourth crab feasts, an uncertain season for Maryland seafood industry," 6 July 2018 Retail auto sales slackened last month, and unsold cars have started accumulating at dealerships. Keith Bradsher, New York Times, "As China Curbs Borrowing, Growth Shows Signs of Faltering," 14 June 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'slacken.' 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 slacken

14th century, in the meaning defined at transitive sense 1

Keep scrolling for more

Learn More about slacken

Statistics for slacken

Look-up Popularity

Time Traveler for slacken

The first known use of slacken was in the 14th century

See more words from the same century

Keep scrolling for more

More Definitions for slacken



English Language Learners Definition of slacken

: to become slower or less active : to slow down
: to make (something) slower or less active
: to become less tight or to make (something) less tight


slack·​en | \ ˈsla-kən How to pronounce slacken (audio) \
slackened; slackening

Kids Definition of slacken

1 : to make slower or less energetic The wind slackened.
2 : to make less tight or firm She slackened the reins.

Keep scrolling for more

More from Merriam-Webster on slacken

Rhyming Dictionary: Words that rhyme with slacken

Thesaurus: All synonyms and antonyms for slacken

Spanish Central: Translation of slacken

Nglish: Translation of slacken for Spanish Speakers

Britannica English: Translation of slacken for Arabic Speakers

Comments on slacken

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


a device or gadget

Get Word of the Day daily email!

Test Your Vocabulary

Words for Summer: A Quiz

  • a closeup of a sunflower
  • Which of the following words means “of or relating to summer”?
How Strong Is Your Vocabulary?

Test your vocabulary with our 10-question quiz!


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!