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

transitive verb

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

intransitive verb

: to become slack or slow or negligent : slow down
: to become less active : slack
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.

treatment that retards tumor growth

slow and slacken also imply a reduction of speed, slow often suggesting deliberate intention

she closed her eyes and slowed her breathing

, 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.
Recent Examples on the Web If the pace of innovation slackened elsewhere, China’s efforts to build LLMs—like a slower cyclist coasting in the leaders’ slipstream—would likely decelerate. Helen Toner, Foreign Affairs, 2 June 2023 And, with the tight job market starting to slacken, some predict 2024 will be the year employers finally clamp down. Tribune News Service, Hartford Courant, 7 Jan. 2024 The tension only begins to slacken with the arrival of FBI agent Tom White (Jesse Plemons). Tom Gliatto, Peoplemag, 19 Oct. 2023 Northwesterly breezes, while not gone, are slackening. A. Camden Walker, Washington Post, 20 Oct. 2023 During the pandemic, the US Food and Drug Administration slackened rules to ease remote care. WIRED, 18 Oct. 2023 Light west-northwest breezes continue but also slacken with time. A. Camden Walker, Washington Post, 21 July 2023 That restless buildup for the perfect tomato to slacken and blush, to actually smell of fire and rain? Eric Kim, New York Times, 19 July 2023 Smoke concentration might increase Wednesday and Thursday as winds are predicted to slacken, according to the MDE, which monitors air quality throughout the state. Dan Belson, Baltimore Sun, 6 June 2023 See More

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'slacken.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History

First Known Use

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

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

Dictionary Entries Near slacken

Cite this Entry

“Slacken.” Dictionary, Merriam-Webster, Accessed 23 Feb. 2024.

Kids Definition


slack·​en ˈslak-ən How to pronounce slacken (audio)
slackened; slackening -(ə-)niŋ How to pronounce slacken (audio)
: to make or become slower or less energetic
slacken speed
: to make less taut : loosen
slacken sail
: to become careless

More from Merriam-Webster on slacken

Last Updated: - Updated example sentences
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