slacken

2 antonyms for slacken — opposites grouped by meaning.

Verb — To slowly lose strength, tightness or speed.

Synonyms by Meaning

To slowly lose strength, tightness or speed.

relax slack slow remit

Opposites

increase

To loosen something, or reduce how tight or strong it is.

Opposites

tighten

increase tighten

This word came from Middle English slakenen, equivalent to slack and -en.

increase slow relax slack tighten remit