verb slack·en \ ˈsla-kən \
Updated on: 9 Jan 2018

Definition of slacken

slackened; slackening play \ˈsla-kᵊn-iŋ\
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

Examples of slacken in a Sentence

  1. Sales show no sign of slackening.

  2. As he began to relax, his grip on the steering wheel slackened.

  3. The captain ordered us to slacken the sails.

Recent Examples of slacken from the Web

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.

First Known Use of slacken

14th century

slacken Synonyms

ease, loosen, relax, slack
strain, stretch, tense, tension, tighten
Related Words
detach, free, unbind, undo, unfasten, untie
Near Antonyms
attach, bind, fasten, tie; constrain, restrain

Synonym Discussion of 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

SLACKEN Defined for English Language Learners



Definition of slacken for English Language Learners

  • : 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

SLACKEN Defined for Kids


verb slack·en \ ˈsla-kən \

Definition of slacken for Students

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

Seen and Heard

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

Love words? Need even more definitions?

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


to make or become suitable or fit

Get Word of the Day daily email!

Test Your Vocabulary

Winter Words Quiz

  • fox-in-front-of-cabin-in-winter
  • Another word for ‘a person who travels to an area of warmth and sun, especially in winter’ is a:
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!