slacken

verb

slack·​en ˈsla-kən 

slackened; slackening 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

Synonyms

• ease
• loosen
• relax
• 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

There’s China, but its demand for oil has slackened markedly amid an economic slowdown. —Neil MacFarquhar, New York Times, 3 May 2025

Retail sales also fell in February, while firms from Walmart to Delta Air Lines have warned of slackening demand. —Khaleda Rahman, MSNBC Newsweek, 2 Apr. 2025

There are some moments that slacken here, especially as Belflower works her way to the twist, but with no intermission, the play’s frenzied pace continues uninterrupted and helps the inevitable revelation land with a real shock. —Lovia Gyarkye, HollywoodReporter, 3 Sep. 2019

But this attempt to freeze Ukraine into submission has failed, and as spring arrives the pressure on power generation will slacken. —David Hambling, Forbes, 19 Mar. 2025

Word History

First Known Use

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

Rhymes for slacken

• blacken
• bracken
• lakin

Kids Definition

slacken

verb

slack·​en ˈslak-ən 

slackened; slackening -(ə-)niŋ 

1

: to make or become slower or less energetic

slacken speed

2

: to make less taut : loosen

slacken sail

3

: to become careless